a.o. smith motors · a.o.smith application motor master y university includes: swimming pools sp a...

52
APPLICATION A.O.Smith Motor Master y University INCLUDES: SWIMMING POOLS SPA & JETTED TUB JET PUMPS INSTALLATION TIPS REPAIR TROUBLESHOOTING OTHER MODULES INCLUDE: HEATING, VENTILATION, AIR CONDITIONING & REFRIGERATION MOTORS GENERAL PURPOSE MOTORS SPECIAL PURPOSE MOTORS PUMP MOTORS A.O. SMITH A.O. SMITH A.O. SMITH A.O. SMITH A.O. SMITH

Upload: others

Post on 26-Oct-2020

2 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

APPLICATIONA.O.SmithMotorMaster yUniversity

INCLUDES:

SWIMMING POOLS

SPA & JETTED TUB

JET PUMPS

INSTALLATION TIPS

REPAIR

TROUBLESHOOTING

OTHER MODULES INCLUDE:

HEATING, VENTILATION, AIR CONDITIONING &

REFRIGERATION MOTORS

GENERAL PURPOSE MOTORS

SPECIAL PURPOSE MOTORS

PUMPMOTORS

A.O. SMITHA.O. SMITHA.O. SMITHA.O. SMITHA.O. SMITH

Page 2: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

ContentsPump Motors

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1Motor Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6Swimming Pool, Spa and Jetted Tub Motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10Service Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11Jet Pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13Motor Troubleshooting Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Recommended Wire Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20Failure to Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20Overheating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21Noisy Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23Electrical Shock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23Protect Against Moisture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23Protect Against Dirt & Chemicals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24Conventional Multimeter or Ohmmeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25Digital Ohmmeter/Multimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25Ammeter and Voltmeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25Voltage Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26Amperage Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26Start Switch Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27Start Switch Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27Motor Component Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29Ground Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29Winding Continuity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30Capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31Protector (Thermal Overload) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32Pump Disassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32

Single Speed Motor — Typical Schematic Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . .33Motor Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36How To Replace Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37Bearing Information Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39Recommended Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39Motor Reassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .402-Speed Motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40Start Switch Replacement and Adjustment — 2-Speed Motors . . . . . . . . . . . . . . . . . . . .41Switch Connections High Speed Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42Switch Connections Low Speed Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .432-Speed Motors High Speed Schematic Diagram (Remote Switch Operation) . . . . . . . . .442-Speed Motors Hi-Low Switch Reconnection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .452-Speed Motors Hi-Low Switch Reconnection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46

© 2001 A.O. Smith Corporation

The information contained in this booklet is general in nature and is drawn from sources believed tobe reliable. It is intended for general information purposes only. The descriptions in this bookletmay not apply to a particular motor or a particular application. No warranties are intended to becreated by this information.

NOTICE:

Page 3: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

IntroductionThe motors discussed in this application mod-

ule are those commonly found on swimmingpools, spas, jetted tubs, home water systems andother centrifugal pumps. The motors are 48 and56 frame used to pump water.

MOTOR TYPESThere are five distinct electrical designs which

may be found on some or all of the pumps beingdiscussed.

1. Split PhaseThis type is used extensively in spa, jettedtub and above ground pool pump applica-tions. Some are used on the lower end of inground pool and jet pumps. This design has astart winding and start switch, but no capaci-tors.

2. Capacitor StartThis is the most common single phase motorfound on in ground pool and jet pump appli-cations. The starting torque is higher (150-175% of full load) and starting current lowerthan the split phase equivalent. The opera-tion is similar to the split phase in that thereis a start switch to take the start windingand capacitor out of the circuit once themotor reaches 2/3 to 3/4 of full speed.

3. Permanent Split Capacitor (PSC)This design does not have a start switch, butuses a run capacitor that remains in the cir-cuit at all times. However, the run capacitoris more expensive than a start capacitor, andthe PSC design has only approximately 40%of the starting torque of a capacitor startdesign.

Pump Motors 1

Level 2 A.O.Smith

Page 4: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

2 Pump Motors

Level 2 A.O.Smith

4. Capacitor Start/Capacitor RunThis design is used to increase efficiency inthe run mode. Both start and run capacitorsare used.

5. Polyphase (3 Phase)This is the simplest, most efficient design.Its use is limited to commercial and industri-al applications since three phase power is notavailable in residential areas.

These same motors may sometimes be appliedto pumps used in other applications where theselection and troubleshooting procedures are sim-ilar, but the application has specific considera-tions due to the fluid being pumped or the oper-ating environment.

Underwriter’s Laboratories has establishedsafety standards for many pump motors.Standard 1081 applies to swimming pool motorsand Standard 778 applies to jet pump motors.

The motors are two pole (3450 RPM) designs ortwo pole/four pole (1725 RPM) designs. The twopole design is used because it runs cooler andmoves more water.

Typical pump motors discussed here use ballbearings at each end of the shaft, one of which islocked to take any thrust loading. Some pumpmotors have had ball/sleeve bearing construction.Jet pump motors typically have double shieldedbearings and pool pump motors typically havedouble sealed bearings. Both types are perma-nently lubricated and neither type is waterproof.

Some pumps utilize a partial motor where thepump provides the shaft extension bearing bore.This type of construction is not popular, andreplacement usage has fallen dramatically. Somereplacement motors are still available. Two basictypes were used in the past. The difference is thelength of the shaft extension.

ST1302CAP START/RUN

PT1072PARTIAL MOTOR

Page 5: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

Pump Motors 3

Level 2 A.O.Smith

The overloads or protectors used on pumpmotors are tested on an eighteen day locked cycletest. The eighteen days simulates a two weekvacation plus weekends and a couple of extradays. During the test, the motor shaft is lockedand power is applied to the motor. Since themotor cannot start, it will heat up rapidly andthe overload will take it off line. After the over-load resets, the cycle is repeated. The motormust operate at the end of the test.

If a motor does not operate because the over-load has failed you should look for other prob-lems. Its failure is often a symptom of anotherproblem.

The pumps are designated centrifugal since themotor spins an impeller which moves the waterby centrifugal action.

Pumps used in these applications are classifiedas centrifugal pumps. A centrifugal pumpderives its name from the principal known ascentrifugal force.

A centrifugal swimming pool pump, in its sim-plified form, consists of two components. Onecomponent is stationary and serves as the hous-ing. It is known as the volute. Inside the voluteis the rotating component known as the impellerwhich is driven by a motor. The motor is the“work horse” of the pump while the impeller isthe “cartwheel” that moves the water.

Page 6: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

4 Pump Motors

A.O.Smith

The principle of operation can be demonstratedby a whirling bucket of water. As the bucket isrotated (figure 1), the water is held in the bucketby centrifugal force. If we were to punch a holein the bottom of the bucket, the water would beforced out, again by centrifugal force (figure 2).Speeding up the rotation of the bucket, the waterwould exit with greater force (figure 3).

This same principle is performed by theimpeller of the pump. As the motor turns theimpeller, the water is forced through the impellervanes toward the outside edge (figure 4). Thespinning action of these vanes generates cen-trigual force (figure 5). This action impartskinetic or velocity energy into the water. As thewater is propelled to the outer edge of theimpeller, there is a reduction in pressure at theeye of the impeller, creating a “vacuum” (figure6).

The combination of atmospheric pressure onthe surface of the water and vacuum at the eye ofthe impeller, causes the water to flow in the “suc-tion pipe” to the pump.

The amount of pressure imparted into thewater by the impeller is determined in part bythe size and design of the impeller which alsoeffects forces placed on the motor. There arebasically two types of impellers used on theseapplications; the semi-open has vanes exposed onthe front or receiving side. The back side isclosed by a shroud (figure 7). A closed impeller isdesigned to have two shrouds completely enclos-ing the vane area of the impeller (figure 8).

IMPELLER

ROTATION OFIMPELLER

FLOWUNDER

PRESSURE

VOLUTE

5

6

Page 7: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

Pump Motors 5

Level 2 A.O.Smith

An open impeller puts a great deal more forceon the motor bearings than does the closedimpeller. A 203 bearing is often used with closedimpeller pumps while open impeller may requirea larger 304 bearing on shaft end. Closedimpeller pumps are used extensively today.

The performance of the pump and motor isaffected by another major factor, the speed atwhich the impeller is driven. The capacity of animpeller varies in proportion to the change in itsspeed.

EXAMPLE:The capacity of an impeller is 50 gallons perminute at a motor speed of 3450 RPM. Itscapacity will drop to 25 GPM if the motorspeed is reduced to 1725 RPM.

The above example is what takes place whenusing a 2-speed motor (3450/1725) for energy sav-ings during low traffic periods on pool or spamotors. The load on the motor is reduced drasti-cally but you also do not get the turn-over rate ofthe high speed.

In the original applications, each motor is test-ed with a specific pump, under a range of operat-ing conditions. Each impeller requires a specificamount of horsepower to turn at a given speed.If a weaker replacement motor is selected thepump’s output will not just be reduced, the motorwill be overloaded. The motor is trying to run atits normal speed around 3450 RPM, and theimpeller needs more power to be driven at thatspeed. If a stronger motor is selected, there willnot be a significant increase in the pump’s out-put. The stronger motor may run a little faster,but the impeller does not need the added horse-power to run around 3450 RPM. In summary,the motor and impeller should be considered amatched set.

7

8

Page 8: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

6 Pump Motors

Level 2 A.O.Smith

ReplacementMotorSelection

Thru Bolt Round Flanged Keyed Round Flanged Threaded Square Flange

REPLACEMENT MOTOR SELECTIONThe nameplate on the motor being replaced

contains much of the critical information neededto select a new motor. Some of the nameplatedata detailed in the Replacement Module isrepeated below in order to reemphasize its impor-tance to the application.

Choosing the right replacement motor is easyusing these 5 steps:1. Know which end frame you need. Is it:

2. Know the total horse-power output.Find it on the motor's name-plate. Use this equation:The total horsepower times(x) the service factor of thereplacement motor must beequal to or greater than thatof the original motor beingreplaced.

3. Is the original motor single or three phase?The original and replacement motors must be thesame unless the power supply is being changed.

4. What is the correct voltage?The operating voltage of the replacement motormust match the voltage of the original motor. Asingle voltage motor is an acceptable replacementfor a dual voltage motor and vice versa.

5. What is the motor's cycle or hertz?As a general rule, 50-cycle motors should not besubstituted for 60-cycle motors and vice versa.

Page 9: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

Pump Motors 7

Level 2 A.O.Smith

SWIMMING POOL, SPAAND JETTED TUB MOTORS

Applications include in-ground pools, aboveground pools and pool cleaners.

There are no efficiency standards for singlephase motors. Motors designated high efficiencyby a motor manufacturer are just more efficientthan their standard motors. Swimming poolpumps are an excellent application for high effi-ciency motors since they typically run manyhours a day, even continuously. Compare theoperating costs of two motors with their purchaseprice.

All commonly used swimming pool, spa and jet-ted tub motors also operate on the principle ofcentrifugal force.

Pool and spa motors are two pole (3450 RPM)designs. The two speed versions are 3450/1725.Four pole windings are used on the low speed.Theoretically, the loading on these pump motorsdrop off at a cubed rate compared to the speed.Examples of horsepower ratings are one (1) HPon high speed and one-sixth (1/6) HP on lowspeed and 2 HP / 1/2 HP.

Pool and spa motors are required to have aground bonding lug. This lug is on the outside ofthe motor and when connected offers visualassurance that the motor is grounded. Beforedoing any work on a pool or jet pump motor,check to see if there is any current leaking toground.

SwimmingPool, Spa andJetted TubMotor s

JBT2072JETTED TUB MOTOR

SQ1072

BONDING LUG

Page 10: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

8 Pump Motors

Level 2 A.O.Smith

In the past when brass pumps were common,the use of motors with cast iron instead of alu-minum end frames was common. The cast ironhas less reaction with the brass. Today, mostpumps are plastic so this is not a concern.

Small above ground pumps have a sealedmotor/pump unit which is not repairable. Motorson the other applications are easily identified bythe type of end frame and shaft extension.NEMA 56C face (56C and 56J) and square flangemotors are common on in-ground pool pumpapplications. Many above ground pool pumpsand jetted tubs use the motor through bolts tosecure the pump to the motor. The motors have a“Y” after the frame designation on the nameplateindicating a non-standard mount. Even thoughthe mount is not standard per NEMA, it hasbecome standard among the pump manufactur-ers. Spas and jetted tubs may sometimes be sim-ilar in looks and construction with the distinctionthat the water is normally drained from a jettedtub after each use. Spas use NEMA C, squareflange and thru bolt mount motors.

Two speed motors are common on single pumpspas. High speed is used for the invigorating jetaction, and low speed is used to circulate waterwhen the heater is on. Less common is the use oftwo speed motors on swimming pools. The unit isrun on high speed several hours a day for maxi-mum filtration action and then switched to lowspeed and run continuously. Some filtrationaction does occur on low speed and a betterchemical balance is maintained. Total electricaland chemical consumption may be reduced.

SK1072

ST1072

SQ1152

CBS2072

Page 11: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

Pump Motors 9

Level 2 A.O.Smith

Pool sweep pumps may use motors with specialflanges and shaft extensions. These are specifi-cally identified in motor manufacturers’ catalogs.

Running a pump dry does not harm the motorwhich is actually operating at a very light load.However, if the seal is damaged by the dry oper-ating condition, it will leak and probably allowmoisture into the motor bearing.

It is not recommended that a jet pump motorbe used as a replacement for a pool pump motoreven though horsepower and mountings may beequivalent. The pool motor will have a groundbonding lug, different ventilation standards forsafety, possibly larger bearings, and a higherambient temperature rating.

Specifics of motor construction, operation,nameplate information, and servicing are coveredin other modules. Following are points which areimportant to reemphasize in relation to pumpmotor applications.

SPS1052POOL SWEEP MOTOR

RPS1052POOL SWEEPMOTOR

PL1072POOL SWEEP MOTOR

Page 12: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

10 Pump Motors

Level 2 A.O.Smith

VoltageVOLTAGE

Most dual voltage (115/230V) motors are con-nected at the factory for 230 volts for two rea-sons. First, the highest percentage of motors areinstalled on the higher voltage. Second, if amotor is connected for 230 volts and 115 volts areapplied in the field, the motor will hum and tripthe overload. If connected for 115 volts and 230volts are applied, it burns out immediately.

Motors are designed to operate at plus orminus 10% of the nameplate rating. This meansthe motor will operate at 103 volts to 126 volts onthe 115 volt connection; and, 207 volts to 253volts on the 230 volt connection. At 207 volts, theamps will be higher and the RPM will be approx-imately 25% lower.

If the system is rated at 208 volts or 200 volts,a motor specifically designed for these ratingsshould be used since the voltage could go as lowas 187 or 180. Specific 208 and 200 volt singlephase motors are not normally stocked forreplacement. The alternative is to use the nexthigher horsepower motor. For example, use a 1horsepower, 230 volt motor when a 3/4 horsepow-er 208 volt motor is needed. Three phase motorshave some greater ability to operate at 208 volts.But, the next higher horsepower should be used ifa 200 volt motor is required.

NEMA no longer recognizes 208 volt systems.The standard is now 200 volts.

Page 13: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

Pump Motors 11

Level 2 A.O.Smith

ServiceFactor

SERVICE FACTORTypical service factors for full rated one horse-

power pool pump motors are 1.65 for squareflange and 1.4 for NEMA C. One horsepower jetpump motors typically have a 1.4 service factor.Over the years, various amp ratings have beenused on motor nameplates. Some motors mayhave rated amps which are amps at one horse-power. This number is basically useless sincethe impeller loads the motor to the service fac-tor. This motor would also have a rating for fullload, service factor or max amps. This is the fig-ure to use when checking a replacement motorafter installation. Some service people make atemporary connection so that the amps may beeasily checked, or the connections are made sothat a loop in the wire is available for checkingamps.

If total horsepower or horsepower times ser-vice factor is difficult for service persons tounderstand, the concept is practically impossibleto explain to a homeowner. If a one horsepowermotor came off the installation, a one horsepow-er must go back on. Uprated motors are ones onwhich the horsepower is increased and the ser-vice factor is decreased. The total horsepowerremains the same. To see how this works, makea copy of a motor manufacturers full rated anduprated motor listings. Put the two listings sideby side so that the one horsepower upratedmotor lines up with the three quarter horsepow-er full rated motor. You will see that the charac-teristics such as amps and weight are the same.The same comparison may be done with pumpcurves.

Page 14: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

12 Pump Motors

Level 2 A.O.Smith

The following chart illustrates the importantfact of comparing total or maximum horsepower:

High Service Low Service

Factor Motor Factor Motor

NEMA

F.L. Std. Motor F.L. Up-Rated

HP SF MAX HP HP SF MAX HP

1/3 1.75 .58 1/2 1.16 .58

1/2 1.60 .80 3/4 1.07 .80

3/4 1.50 1.13 1 1.13 1.13

1 1.40 1.40 1-1/2 1.00 1.50

1-1/2 1.30 1.95 2 1.00 2.00

High Service Low Service

Factor Motor Factor Motor

Higher than

F.L. NEMAS.F. F.L. Up-Rated

HP SF MAX HP HP SF MAX HP

1/3 1.95 .65 1/2 1.30 .65

1/2 1.90 .95 3/4 1.27 .95

3/4 1.65 1.25 1 1.25 1.25

1 1.65 1.65 1-1/2 1.10 1.65

1-1/2 1.47 2.20 2 1.10 2.20

2 1.30 2.60 2-1/2 1.04 2.60

Uprated

Uprated

Uprated

Uprated

Uprated

CAPACITORSIt is recommended that replacement capacitors

be of the same MFD and voltage rating as theoriginal. If the exact replacement is not avail-able, it is recommended to use one with a MFDrating not more than 10% greater. Using onewith a larger value could make the motor run hotand loose torque. The voltage rating should alsovary only on the high side. In some cases, it willbe necessary to go beyond 10%. Example, if a370 volt unit is not available, the next rating is440 volt.

Uprated

Uprated

Uprated

Uprated

Uprated

Uprated

Page 15: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

Pump Motors 13

Level 2 A.O.Smith

JET PUMPSThe two most popular types of home water sys-

tems have their water delivered and pressuredeveloped by either a jet pump or submersiblepump.

As the name implies, the submersiblepump/motor unit is located in the water supplyand connected to a waterproof electrical supply.

The jet pump/motor unit may be located in thehome, or outside if there is little risk of freezing.In freezing areas, the pump may be located out -side in a pit which is covered and protected fromfreezing.

Most jet pumps use open drip proof motors(ODP). When used in a vertical application out-doors, a different or additional rain canopy isrequired. A separate “dog house” or motor coversuch as the Blue Devil™ unit shown here provideprotection from the elements and improves motorlife. Motor covers must allow free air flow so thathot air from the motor is not recirculated, short-ening motor life.

Jet pumps are called single stage if they haveone impeller and multi-stage if there are two ormore impellers.

The motor shaft is parallel to the ground in ahorizontal jet and vertical in a vertical jet.

All jet pump motors are two-pole (3450 RPM)designs.

Jet Pumps

8200 MC-200UNIVERSAL MOTOR COVER(fits 1/3 HP to 2 HP motors)

Page 16: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

14 Pump Motors

Level 2 A.O.Smith

Most jet pumps use NEMA C face (56C or 56J)or square flange motors. Most square flangemotors have 1/2-20 threads but some have 7/16-20 threads. Many other centrifugal pump appli-cations such as lawn sprinklers and irrigationuse jet pump type motors.

Jet pump motors typically have shielded bear-ings while swimming pool pump motors havesealed bearings. Both types of bearings are per-manently lubricated and neither is waterproof.

Running a pump dry does not harm the motorwhich is actually operating at a very light load.However, if the seal is damaged by the dry oper-ating condition, it will leak and probably allowmoisture into the motor bearing.

Jet pumps operate on the principle of centrifu-gal force. The motor spins the impeller whichdoes the work.

Jet pumps get their names from the principle ofoperation in which a stream of water is pushedthrough a nozzle into a diffuser creating an areaof low pressure. This low pressure draws addi-tional water from the supply (usually a well).

The action of getting water from the well intothe pump system is caused by air pressure. Atsea level, air has enough pressure to lift a columnof water thirty-four (34) feet. Because of differ-ences in air pressure, elevation and system effi-ciencies, most jet pumps have an arbitrary liftrating of twenty-five (25) feet.

T1072JET PUMP MOTOR

Page 17: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

One way of visualizing the action is comparingit to drinking from a straw. The partial vacuumcreated when you suck on the straw causes thedrink to be forced up the straw by air pressure. Ifthe container from which you were attempting todrink were sealed, liquid would not be drawn intoand up the straw.

Jet pump systems may be shallow well or deepwell. In shallow well systems the jet assembly islocated on the pump. In deep well systems thejet assembly is located in the well, normallybelow water level. If the water level falls morethan twenty-five below the jet during pumping ordraw down, the pumping action will slow andeventually stop as the water level in the well con-tinues to drop.

Convertible jet pumps may be configured foreither shallow or deep well applications.

Shallow well systems use one pipe into thewater source and deep well systems use twopipes. One pipe provides water to operate the jetand the second pipe carries water to the surface.Systems known as packers are deep well systemswhich use the well casing itself as one of the twopipes.

A pitless adapter is a fitting which goesthrough the well casing below the frost line. Thepart inside the well has two pieces, with an O-ring seal, which slide apart. A piece of pipe isthreaded into the top of the adapter so that themovable part and the pipe or pipes extending tothe water may be removed. The use of a pitlessadapter allows the pipe or pipes going to thepump to be buried below the frost line.

PITLESS ADAPTER

GROUNDLEVEL

FROSTLINE

WATER LEVEL

CHECK (FOOT)VALVE

PITLESSADAPTER

TO HOUSE

LIFTPIPE

Pump Motors 15

Level 2 A.O.Smith

Page 18: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

16 Pump Motors

Level 2 A.O.Smith

A check valve or foot valve is normally locatedin the plumbing line before the pump. This “oneway” valve is needed so that the pressure in thesystem will not bleed off when the pump stops. Ifthe valve leaks, the pump will start and stop,even through water is not being used.

Since for all practical purposes, water is noncompressible, a pressure tank is used in the sys-tem.

A pressure switch is used to start and stop themotor. The “cut in” setting is the pressure atwhich the motor starts. The “cut out” setting isthe pressure at which the motor stops. Theamount of water (in gallons) that is pumped ineach cycle is called draw down. In a specific sys-tem, the draw down amount may be varied bychanging the cut in and/or cut out settings.

The low and high pressures of the system aredetermined by the cut in and cut out settings, notby the amount of air pressure in the system.

As water is pumped, air in the tank is com-pressed until system pressure reaches the cut outlevel. The most popular tanks have a bladder ordiaphragm which separates the air and water.Other systems use an air volume control and putair into the tank each time the pump is started.If the water and air were not separated, or airwas not added, the air in the tank would all dis-solve in the water and the tank would become“waterlogged”.

If the air charge in a system is reduced, thepump will still start and stop at the same pres-sures, but less water will be pumped in each cyclebecause there is less air to compress. As theamount of air is decreased, the tank approaches awaterlog condition and the system operates as ifthere were no pressure tank.

AIR

WATER

AIR

WATER

DIAPHRAGM

TO HOUSE

PUMPSIDE

DIAPHRAGMPRESSURE TANK

30 PSI CUT IN50 PSI CUT OUT

HOUSE PUMPSIDE

AIR

WATER

HOUSE PUMPSIDE

BOTH AIR AND WATER AT 40 PSI

1. FAUCET OPENED2. AIR PUSHES ON DIAPHRAGM3. WATER SENT TO SYSTEM4. AT 30 PSI, PUMPSTARTS

AT 50 PSI,PUMPSTOPS

Page 19: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

Pump Motors 17

Level 2 A.O.Smith

The primary function of the pressure tank is toprotect the pump motor. Without a tank, pres-sure in the system would drop to zero almostimmediately when a faucet was opened. Then,almost as quickly, the cut out pressure would bereached and the pump would shut off. The cyclewould repeat as long as the faucet remainedopen. This is the same thing that happens whena pressure tank becomes waterlogged.

Short or rapid cycling is hard on the pumpmotor whose windings are subjected to startingor in rush current levels on an almost constantbasis. The start capacitor will often fail becauseits duty cycle is exceeded. They are rated attwenty starts of three second duration per hour.Rapid cycling causes heat to build up which maycause failure. Premature wear also occurs on thestart switch.

When a pump’s flow decreases, the pressureincreases to a point known as shut off. This pres-sure may be many times the cut out pressure set-ting. Water hammer is caused by flowing waterin a system suddenly being stopped. Water ham-mer can cause sudden pressures as high as 760PSI with system pressure of only 60 PSI. Sincethere is a delay between the time the pressureswitch senses cut out and the time the pumpactually stops, water hammer will occur.

The shut off point may be determined by agauge with the pump running against a closeddischarge. This point could also be found bylengthening a vertical discharge pipe to the pointwhere the pump is unable to cause water to flowfrom the top.

Page 20: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

18 Pump Motors

Level 2 A.O.Smith

When running at shut off the energy is convert-ed to heat. The water in the pump casing canboil under pressure to the point where a plasticimpeller is melted. Some of the heat goes intothe motor shaft and back to the bearing causingpossible failure.

If a jet pump is used as a centrifugal pumpwith the jet assembly removed, the motor mayoverload particularly in a flooded suction condi-tion. Flooded suction means water is available tothe pump without the pump having to create asuction lift.

Jet pump motors may be either single voltage(115 or 230 for example) or dual voltage(115/230). On original equipment, 115 volt 1/3and 1/2 HP units are common since there isenough volume to warrant a separate model witha slightly lower motor cost. Most replacementmotors are dual voltage and factory connected forhigh voltage. If 115 volts are applied to a motorconnected for 230 volts, the motor will just humand probably not turn. In the reverse condition,the motor will immediately burn out.

The motor will not run faster or be more effi-cient on the high voltage, but a smaller wire sizemay be used since the amps at 230 volts are one-half the amps at 115 volts.

A dual voltage motor is sometimes temporarilyrun on low voltage at a new home site until thepermanent power supply is available.

Page 21: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

Pump Motors 19

Level 2 A.O.Smith

MotorTroubleshooting

GuideThere is not a single listing of motor trou-

bleshooting procedures to be followed in a givenorder. The procedures will also differ for new andexisting installations, and motors that are beingbench checked. As with anything dealing withelectricity, personal safety is the prime concern.

Checking a motor in its application is the onlypractical method for most people to determineperformance under load. If the motor is defec-tive, the application provides many clues to helpdetermine the cause. Did the motor fail due to adefect or old age, or was its failure hastened bythe application or environment? The applicationis the only place an attempt may be made tocheck voltage.

On permanently installed equipment, the volt-age may vary depending upon the total systemload. It can also vary with the total load on thepower company grid.

While some of the troubleshooting proceduresthat follow apply specifically to the two compart-ment A.O. Smith pump motor, the basics apply toother motors.

WARNING!This is not a guide forthe do-it-yourselfer.These tips and sugges-tions are offered forpersons with properqualifications andnecessary test equipment.

Page 22: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

20 Pump Motors

Level 2 A.O.Smith

See that this electrical list is followed:■ Assure proper voltage at motor terminals.■ Follow motor connection diagram on motor nameplate.■ Make sure motor is properly GROUNDED and complies

with local and national electrical codes.■ See that the pump turns freely before starting motor.

FAILURE TO START (MOTOR MAKES NO SOUND)■ Check voltage at motor line terminals. Voltage should cor-

respond with motor nameplate rating (+10%).■ Check all electrical connections at the motor terminal

board.■ If no voltage is present; check fuses, timers & switches.■ Protector tripped — wait until motor cools then restart —

check protector for continuity.

The following chart shows recommended minimumwire sizes for pump motors. The calculations were based onmotors with the highest starting currents. Larger wire sizesreduce the voltage drop at the motor in both the start and runmodes. A lower voltage drop means the motor will run moreefficiently (cooler) and have increased service life. In general,and up to a certain point, the efficiency gained from one sizelarger wire will have a payback of less than two years.

PUMP MOTOR RECOMMENDED MINIMUM WIRE SIZE*

*Always follow all applicable codes.**Pump Motors with service factors greater than 1, and split phase designs.No more than 15 volts drop at start, in worst case.

DISTANCE FROM SERVICE ENTRANCE/MAIN PANEL TO MOTOR

50 feet 100 feet 150 feet 200 feet

115V 230V 115V 230V 115V 230V 115V 230V

1/3 14 14 12 14 10 12 8 12

1/2 14 14 10 14 8 12 8 10

3/4 12 14 10 12 8 12 6 10

1 12 14 8 12 8 10 6 8

1-1/2 10 14 8 12 6 10 6 8

2 10 14 8 10 6 10 6 8

3 12 10 8 8

MotorH.P.**

$

Page 23: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

Pump Motors 21

Level 2 A.O.Smith

FAILURE TO START (MOTOR HUMS OR ATTEMPTS TO START)■ Check voltage at motor line terminals. If

voltage is inadequate to start motor, check forloose connections, undersized wiring, over-loaded circuit or other causes of voltage drop.

■ Start switch contacts not closed when motoris not operating. Switch may require adjust-ment. Switch contacts dirty or pitted.

■ Capacitor (where used) is “shorted” or “open”.■ Check motor windings for “open” or “short”.■ Check for continuity through protector.■ Turn the motor shaft by hand to get the “feel”

of the motor. If the shaft feels tight or doesn’t turn smoothly:• Check the bearings for smooth operation.• See if there is evidence of the rotor

striking the stator.• Check for internal corrosion, cracked end

frames, clogged fan or other obstruction within the motor.

• Check pump for obstructions, binding impeller, or bent shaft.

OVERHEATINGAs in all motor applications, excess heat is very

detrimental to motor operation and life. Heatover time breaks down motor insulation andleads to failure. The relationship of temperatureto life is geometric. In other words, as the tem-perature goes up the winding life is shortened atan increasing rate.

A continuously running pump motor may behot to the touch and this by itself does not meanthe motor is overheating.

Excess heat has many possible causes:■ Low voltage. The voltage may be low at the

source or there may be excessive voltage dropwhen the load is applied due to too small awire size.

Page 24: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

22 Pump Motors

Level 2 A.O.Smith

■ Overvoltage. This needs correction by thepower company.

■ High ambient temperature. Pool motors arenormally designed to operate in higher ambi-ents (50˚C) than jet pump motor which usual-ly have short duty cycles. Artificially highambients may be created if the motor oper-ates in a confined space and recirculates theair.

■ Protect the motor from excess heat by shad-ing from the sun with a motor cover such asthe Blue Devil™ unit illustrated here. It isimportant that a motor cover provides freshair circulation and does not allow air heatedby the motor to recirculate.

■ Reduced air flow. Foreign material such asgrass clippings, leaves, lint and bugs andsmall lizards may plug air passages.

■ If the motor has an internal cooling fan, is itintact and functioning properly?

■ Application overload. In cases of flooded suc-tion or positive pressure on the inlet to thepump, flow may be increased, overloading themotor.

■ Misapplication. Specific motor and impellercombinations are sized to do a specific job. Inmost cases, the impeller loads the motor tothe service factor horsepower. It is absolutelyimperative that a replacement motor is ableto develop the same or higher total horsepow-er (nameplate horsepower X service factor) asthe motor being replaced.

■ Compare the running amperage of the motorwith MAXIMUM LOAD or SF amps. Ifamperage is higher than MAXIMUM LOADor SF amps, with proper voltage applied,determine cause of overload.

8200 MC-200UNIVERSAL MOTOR COVER(fits 1/3 HP to 2 HP motors)

Page 25: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

Pump Motors 23

Level 2 A.O.Smith

■ Check motor windings and capacitor (whereused) for “ground” or “short”.

■ Check terminal board connections with themotor wiring diagram for proper applied volt-age.

■ Check the motor start switch and governor tobe sure it is adjusted properly and is opera-tional.

NOISY OPERATION■ Check motor coupling, brackets and other

attached parts for adjustment or looseness.■ Motor bearings.■ Pump cavitation.

ELECTRICAL SHOCK■ Check motor windings, all motor wiring, and

capacitor for ground.

PROTECT AGAINST MOISTURE■ The open drip proof type motors discussed

here may be used outside, but their lifeexpectancy is enhanced if they are protectedfrom the elements. The enclosures should notrestrict air flow or cause recirculation.

■ Motors that are out of service, such as poolmotors in the winter, should not be sealed inplastic bags which cause condensation direct-ly in the motor.

■ If the motor is not running it may be coveredfor short periods of time such as when thearea around a swimming pool pump is beinghosed down.

Page 26: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

24 Pump Motors

Level 2 A.O.Smith

■ Locate motor on a slight elevation so waterwill not run or puddle nearby.

■ Avoid spilling or dripping liquid chemicals onor near the motor.

■ Avoid splashing water on or near the motor.■ Repair leaky pipe joints, “O” rings, or pump

seals promptly.■ Avoid locating motor in highest humidity

area.

If the motor is flooded, the bearings may beruined. Once they start making noise, failure isimminent.

If the seal leaks and is not replaced, the bear-ings may also be ruined. A new seal should beinstalled any time a motor is replaced. A slingeror flinger should also be used on the motor shaftto deflect water from the bearing location.

PROTECT AGAINST DIRT & CHEMICALS■ Avoid sweeping or stirring dust near the

motor while it is running.■ Chemicals should not be stored near the

motor. Chlorine can be especially damagingif in a liquid form being dispensed into a filter pit.

ELECTRICAL CHECKSThe next section explains the use of test

equipment.

Page 27: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

Pump Motors 25

Level 2 A.O.Smith

CONVENTIONAL MULTIMETER OR OHMMETERAn ohmmeter can be used to measure the resis-

tance of the various motor windings as well as totest the insulation.

The ohmmeter will have numerous ranges fromR x 1 where the meter reads directly in ohms toan Rx100K where the actual meter reading mustbe multiplied by 100,000 for the actual ohmvalue.

Before using an ohmmeter:■ Make sure all motor leads are disconnected

from the power source.■ Make sure the meter is adjusted to zero

before taking each reading.■ All troubleshooting checks specify the ohm-

meter range to be used. If your meter doesnot have the exact range, use the next higherrange.

DIGITAL OHMMETER/MULTIMETERDirect reading digital ohmmeters are readily

available in the field. To use this type:■ Make sure all motor leads are disconnected

from the power source.■ Read instruction manual for the meter.■ You do not have to set the ohmmeter to a par-

ticular scale as the meter displays the ohmvalue up to the maximum capability of themeter.

■ Install probes and take resistance readings inthe normal manner.

AMMETER AND VOLTMETERVoltmeter Readings:Install leads in bottom of Amprobe®. Select the

desired voltage scale. Take readings by touchingone probe to each of the lead line terminals.

Ammeter Readings:■ Arrange leads so the jaws of the Amprobe®

will encircle one lead.■ Set meter on maximum amp scale and encir-

cle jaws around one lead and take reading. Itmay be necessary to reset to a lower scale.

Page 28: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

26 Pump Motors

Level 2 A.O.Smith

VOLTAGE CHECK■ Disconnect power source■ Remove canopy■ Determine motor voltage and set meter

on proper scale■ Reconnect power■ Start motor

Touch one probe to L1 and the other to L2.Voltage reading to be within 10% of nameplatevoltage, i.e. between 207 and 253 volts for a 230volt motor.

If no voltage is recorded, check pressure switch,fuses, circuit breakers, timers, wiring, etc. foropen connection or broken wires.

If voltage is outside the acceptable limits-checkfor adequate wire size. Look for loose terminalsand connections, or pitted contacts, check pres-sure switch and pump disconnect switch.

Check voltage at service entrance. If not with-in +10% contact power company.

AMPERAGE CHECK■ Turn off power at pump disconnect switch.■ Set ammeter scale based on max. load amps.■ Position one line lead (L1 or L2) so that jaws

of amprobe can encircle one power lead.■ Make sure switch and governor are free of

obstructions.■ Reconnect power.■ Start motor.■ Encircle one line lead with jaws of amprobe

and take reading. This value should notexceed maximum load amps of motor.

Excessive amps means an overloaded conditionor incorrect voltage applied. Problem could alsobe in motor.

Page 29: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

Pump Motors 27

Level 2 A.O.Smith

START SWITCH CHECK■ Visual checks:

• Disconnect power source.• Remove canopy.

■ Make sure there are no obstructions preventingthe proper operation of the rotating governor.Check wiring and make sure none of the leadsare in the area of the governor where they canbe cut or interfere with the governor. Checkgovernor for proper operation and make sureflipper is free to move.

■ Check switch contacts for severely burned orpitted contacts, sticking etc. Some blackeningor pitting is normal after motor has been used.Replace switch if there is any doubt. Don’t tryto repair by bending the contact leaf.

■ Unlike points in an automotive distributor, theswitch contacts in motors are plated and shouldnever be sanded which would remove the plat-ing and cause early failure. They may becleaned by wiping with a piece of cardboard orpaper bag.

■ Reconnect power.■ Start motor. Visually check the action of the

switch and governor. Switch contacts must beclosed when motor is at rest and should openwhen motor reaches about 2/3 of full loadspeed.

START SWITCH ADJUSTMENT■ Fasten switch snugly to end bell, through “U”

bracket with the screw provided.■ A slight amount of switch movement is possible

before the screw(s) is tightened. Check to seethat the white switch button is centered overthe governor projection.

■ Reach in and move the governor weight (over-coming the spring tension) until it touches thestops on the governor.• The clearance between the projection

and the white button should be .010”to .040” (.040 is about the thickness of paper clip wire).

NOTE: Replace capac-itor and switch at thesame time. A defectiveswitch usually stressesthe start capacitor.

Page 30: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

28 Pump Motors

Level 2 A.O.Smith

■ Most newer models use only one screw tosecure and adjust the switch. When a newswitch is installed, or an existing switch isbeing reinstalled, the "U" bracket should beopened slightly to insure sufficient tensionagainst the screw. Tighten only when adjust-ing. If the screw is loosened, it should beremoved and the "U" bracket should again beopened slightly.

■ On models with two screws, turn the switchadjustment screw until the correct clearanceis obtained. When finished, tighten the adja-cent switch screw to secure the switch to thebracket.

■ Under no circumstances should switch con-tact leafs be bent or deformed in an attemptto obtain proper contact clearance.

WHITE PLASTIC BUTTON

GOVERNOR PROJECTION

MOTOR SHAFT

START SWITCH

"U" BRACKET

SWITCH ADJUSTING SCREW—TIGHTEN ONLY—

.010”

.040”

GOVERNOR WEIGHT

REMOVE AND OPEN "U" BRACKET SLIGHTLY TO INSURESUFFICIENT SCREW TENSION WHEN INSTALLING NEWSWITCH OR AFTER SCREW HAS BEEN LOOSENED.

Page 31: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

Pump Motors 29

Level 2 A.O.Smith

MOTOR COMPONENT CHECKSBased on your observations perform the follow-

ing checks to confirm that each component isfunctioning properly.

GROUND CHECKGround Check — Set ohmmeter to R x 1K.

■ Attach one probe to ground screw and touchother probe to all terminals on terminalboard, switch, capacitor and protector. Areading of less than 10K could indicate aground. New motors typically read over onemegohm. Old motors with dust, dirt andmoisture could show resistance to groundbelow 10K and still run satisfactorily. Acleaning may be in order. Readings may varyfrom day to day depending upon the humidi-ty levels. Approximately 25K at 115 voltswill trip a ground fault device. Keep in mindthe ground fault device is seeing the totalleakage of all loads on the circuit. GFI's nor-mally trip on readings from 4 to 6 milliamps.

■ If grounded, check all external leads for cuts,breaks, frayed wires, etc. Replace damagedleads and recheck for grounds and properlead routings. Make sure replaced leads arenot pinched between canopy and end bell.If ground is in stator, replacement of motor isrecommended.

Page 32: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

30 Pump Motors

Level 2 A.O.Smith

L1 TO REDYELLOW TO RED

Resistance between L1 and A must be same as between A and yellow.

Yellow to red (winding side of switch) must be same as L1 to same red terminal.

WINDING CONTINUITY(For typical single phase, dual voltage only, capaci-

tor start, single speed motor, connected for 230V.Set meter to R x 1).

For single voltage motors, check between L1 andL2.

Slip a heavy piece of paper between points, takingcare not to bend tabs. Discharge capacitor by short-ing across the terminals with the blade of an insu-lated screwdriver. Take the following ohm readings.

Page 33: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

Pump Motors 31

Level 2 A.O.Smith

CAPACITORCapacitor — Set ohmmeter at R x 1K.Slip a heavy piece of paper between points.Discharge capacitor by touching the two termi-

nals with the blade of an insulated handle screw-driver.■ Attach one probe to each terminal; ohmmeter

needle should move rapidly to right thenslowly drift to the left. (Low ohm reading tohigh ohm value).

■ If a digital meter is used, readings shouldstart low and rapidly increase to maximumvalue.

■ Replace capacitor if bad.

SWITCHRemove paper and attach one lead to each

switch terminal. Ohmmeter reading should be 0.Flip governor weight to running position.Reading should be infinity.

Page 34: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

32 Pump Motors

Level 2 A.O.Smith

PROTECTOR (THERMAL OVERLOAD)Protector — Set ohmmeter to R x 1.Resistance between protector terminals:1 & 2 should be approximately 0 (Disc.).2 & 3 should be approximately 0 (Heater).Replace if either value exceeds 1 ohm.

NOTE: Motor cyclingon overload indicatessome other problem, notjust a defective over-load.

1 & 2

PUMP DISASSEMBLYWrench flats on shaft have been provided to

facilitate impeller removal. Insert a 7/16” openend wrench under governor assembly and holdwhile unscrewing impeller. (NOTE: For easieraccess, the capacitor can be removed from itsmounting bosses).

NOTE: If necessary toremove motor frompump, disassemblepump in accordancewith pump manufactur-er’s recommendation.

* Motors produced since2000, have an improvedwrench access areabehind the overload.

*

Page 35: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

Pump Motors 33

Level 2 A.O.Smith

SINGLE SPEED MOTOR — TYPICAL SCHEMATIC DIAGRAMSCapacitor Start

Induction Run — Single Speed

EXT. & WIRE ROUTINGDual Voltage — Single Speed — Capacitor Start

With Voltage Change Plug

Page 36: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

34 Pump Motors

Level 2 A.O.Smith

Capacitor StartCapacitor Run — Single Speed

SWITCH

RUN. CAP.

Page 37: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

Pump Motors 35

Level 2 A.O.Smith

SINGLE SPEED MOTOR — TYPICAL SCHEMATIC DIAGRAMSCapacitor Start* or Split Phase

Single Voltage on Winding Protector

*Capacitor not shown in schematic.

SWITCH

Page 38: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

36 Pump Motors

Level 2 A.O.Smith

MOTOR ASSEMBLYAll of the motors covered by this manual are

similar in design and construction, with varia-tions in baffles, type of protector, type of flange,and bearing construction. When disassembling,make sure you note the exact location of all com-ponents so they can be reassembled in the properorder. This is especially true of the bearingassembly where the number and types of smallparts (rings, washers, etc.) varies substantiallyfrom model to model.

Page 39: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

Pump Motors 37

Level 2 A.O.Smith

HOW TO REPLACE BEARINGS1. Remove the bearing(s) from the

motor shaft following these stepsas necessary:■ Use an external ring pliers to

remove snap rings which areused to secure bearings.

■ Use a bearing puller toremove defective bearing(s).Don’t reuse a bearing whichhas been removed from theshaft.

■ Remove miscellaneous smallparts (washers, etc.) fromshaft after bearings areremoved. Be sure to replacein proper order.

2. Install the new bearing(s) usingthe motor illustration and typicalbearing installation view as anassembly guide. Follow thesesteps as necessary.■ Refer to the table for the size

tube needed to install newbearing(s). It is important topress only on the bearinginner race. The bearing willbe damaged if the outer racesurface is used for pressing.

■ Fan end: Place the short endof the shaft on the woodblock. Place the bearing (andother parts as used) over thelong end of the shaft. Tapthe bearing into place usingthe proper size tube and amallet, or use a press.Attach any parts (as used) tothe long shaft end.

RINGS, BEARINGS,SHIELD AND SPACERARE OFF SHAFT END

WOOD BLOCK

BEARINGINSTALLATIONTUBE (SEETABLE 1)

NOTE: SNAP RINGS ARE USEDON SOME MODELS TOLOCATE BEARINGSRATHER THAN A SHAFTSHOULDER

BEARING

SHORT SHAFT END

ROTOR

FAN

LONG SHAFT ENDWOOD BLOCK

ROTOR

FAN

RING

SHIELD

BEARING

LONG SHAFT END

LOCK PLATE

Page 40: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

38 Pump Motors

Level 2 A.O.Smith

• Opposite end: Place the long end of theshaft on the wood block. Place the bear-ing (and other parts as used, such assnap rings and washers) over the shortend of the shaft. Tap the bearing intoplace using the proper size tube and amallet, or use a press. Attach any otherparts (as used) to the short shaft end.

Compare the rotor and shaft parts assemblyshown on the previous pages with the order ofassembly found on the motor during teardown.The miscellaneous parts (washers, snap rings,etc.) vary from motor to motor, so when disassem-bling use care to identify these parts and theirorder so they can be reassembled in the propersequence.

Page 41: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

Pump Motors 39

Level 2 A.O.Smith

BEARING INFORMATION TABLE

1. Only use bearings obtained from A.O.Smithand ordered by the proper A.O.Smith partnumber. Do not substitute other bearings, orreuse bearings which have been pulled fromshafts. Bearings obtained from A.O.Smithare built with balls having a specific fit,checked for sound level and filled with highgrade grease for the temperature and serviceconditions.

2. Replacement instructions show how the bear-ing installation tube is used to install newbearings.

RECOMMENDED TOOLS

Bearing Installation Tube Dimensions(In Inches)2Bearing Dimensions

A.O. SmithBearing

Part No.1Outer

Diameterof Tube

WallThickness

MinimumLength

BearingSize Width

(Inches)

Diameter (Inches)

Inside Outside

202-16

203

204

304

205

.6299

.6693

.7874

.7874

.9843

1.3780

1.5750

1.8504

2.0472

2.0472

.4331

.470

.5512

.5906

.5706

610358-1

604005-4

600269-2

603628-2

612096-1

7/8

1

1-1/4

.095

.095

.125

3

3

3

EXTERNALRING PLIER SNAP-ON TOOLSMODELNO. PRS 22 OR EQUAL

TRU-ARC PLIERS

BEARING INSTALLATION TOOLS

BEARING PULLER SNAP-ONTOOLSMODEL NO. CG-250 OR EQUAL

Page 42: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

40 Pump Motors

Level 2 A.O.Smith

CAUTION: Whenrouting leads under thecanopy be sure that:A. No leads are in the

area of the rotatinggovernor.

B. When the canopy isinstalled make sureleads will not bepinched between thecanopy and the endframe.

NOTE: In either casethe fault could cause aground, resulting in avery dangerous conditionshould power be appliedwithout proper ground-ing.

MOTOR REASSEMBLYReassemble the motor in reverse of the disas-

sembly procedure.■ Observe all reassembly precautions and

adjust the motor start switch.■ Recheck wiring.■ Check rotor and shaft and make sure it turns

freely by hand.■ Check motor for grounds before applying

power.

2-SPEED MOTORSTwo-speed motors are regulated by various

types of controls which range from a simple“high-low” toggle switch to elaborate and exoticautomatic systems. Thus troubleshooting two-speed systems requires an extensive knowledgeof both motors and controls.

Two-speed motors are built with and withouthigh-low switches. The conversion of a “with”switch motor to “remote” switch operationrequires more than just removing the switch.Schematic diagrams are included in this sectionfor conversion purposes.

Capacitor start — Motors of this design have amodel number beginning with C (i.e., C48 or C56)and usually start on the high speed (2-pole)winding.

Split phase — a split phase motor (S48) alwaysstarts on high speed. There is no start capacitor,therefore, the red tracer lead from the startwinding connects directly to terminal #2 on theswitch.

Capacitor start and run — motors of thisdesign have a model number beginning with K(i.e., K48 or K56) and will have a run capacitormounted on the exterior of the motor.

Thermal protector — 2-speed motors alwayshave the thermal protector located on the motorwindings.

Page 43: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

START SWITCH REPLACEMENT AND ADJUSTMENT — 2-SPEED MOTORSProper starting switch adjustment on two-speed motors is essential for

satisfactory operation and contact life.■ Disconnect all power to the motor before attempting any repair. Repair work

should only be performed by a qualified electric motor technician.■ Fasten switch snugly to end bell, through “U” bracket with the switch mounting

screw provided.■ A slight amount of switch movement is possible before the screw(s) is tightened.

C h e ck to see that the white switch button is centered over the governor projection.■ Lift the governor weight (overcoming spring tension) until it touches the stops

on the governor. Clearance between the governor projection and white buttonshould be .010” to .040”.

■ Most newer models use only one screw to secure and adjust the switch. When anew switch is installed, or an existing switch is being reinstalled, the "U" bracketshould be opened slightly to insure sufficient tension against the screw. Tightenonly when adjusting. If the screw is loosened, it should be removed and the "U"bracket should again be opened slightly.

■ Under no circumstances should switch contact leafs be bent or deformed in anattempt to obtain proper contact clearance.

■ Once the governor weight is released, and the governor projection pushes on theswitch button, contact Z should move away from the motor by approximately.030”. This movement assures that the points will have sufficient contact nomatter what position the rotor/shaft and governor projection are in at rest.

In run position contacts X & Y must be open and contact Z closed. At rest,contacts X & Y must be closed and contact Z open.

Pump Motors 41

Level 2 A.O.Smith

SWITCH ADJUSTMENT

SWITCH ADJUSTING SCREW—TIGHTEN ONLY TO OBTAIN PROPER CLEARANCE—

WHITE SWITCH BUTTON

X

Z

Y

SWITCH ASSEMBLY

SWITCH MOUNTING “U” BRACKETGOVERNOR ASSEMBLY SHOWNIN OPEN POSITION

CLEARANCE WHENACTUATOR IS INRUN POSITION ASSHOWN

.010

.040

START CONTACTS

REMOVE AND OPEN "U" BRACKET SLIGHTLY TO INSURESUFFICIENT SCREW TENSION WHEN INSTALLING NEWSWITCH OR AFTER SCREW HAS BEEN LOOSENED.

Page 44: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

42 Pump Motors

Level 2 A.O.Smith

SWITCH CONNECTIONS — HIGH SPEED START

WHITE

(COMMON)

(FROM START WINDING)RED TRACER

BLACK TO #3

YELLOW TO #1

(4 POLE MAIN)

(2 POLE MAIN)

STARTCAPACITOR

LOW

HI

YELLOW TO #5

YELLOW TO #1 TO #5

TERMINAL #1

TERMINAL #5

TERMINAL #4

TERMINAL #3

TERMINAL #2

BLACK TO #4

RED TO #2

END VIEW

TOP VIEW

Page 45: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

Pump Motors 43

Level 2 A.O.Smith

SWITCH CONNECTIONS — LOW SPEED STARTLow speed start — this design motor always

starts on the low speed (4-pole) windings. Whenthe control calls for high speed run, the startswitch automatically switches the motor to high.

WHITE

(COMMON)

LOW

HI

YELLOW TO #4BLACK TO #5

BLACK #1 TO #5

TERMINAL #1

TERMINAL #5

TERMINAL #2

BLACK TO #1(2 POLE MAIN)

(4 POLE MAIN)

RED TRACER(FROM START WINDING)

YELLOW TO #3

RED TO#2

YELLOW TO #4

TERMINAL #3

TERMINAL #4

TOPVIEW

END VIEW

Page 46: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

44 Pump Motors

Level 2 A.O.Smith

2-SPEED MOTORS — HIGH SPEED STARTSCHEMATIC DIAGRAM

2-Speed for Remote Switch Operation

LINE VOLTS(HIGH SPEED)

LINE VOLTS(LOW SPEED)

BLACK

YELLOW

START - X & Y CLOSED ZOPENRUN - X & Y OPEN Z CLOSED

BLACK

REDCAPACITOR

START

HI

YX

WHITE

Z

Page 47: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

Pump Motors 45

Level 2 A.O.Smith

2-SPEED MOTORS — HIGH SPEED START SCHEMATICDIAGRAMS AND RECONNECTION INSTRUCTIONS FOR

REMOTE OPERATION2-Speed with Hi - Low Switch

Mounted on Motor Canopy

RECONNECTION FOR REMOTE SWITCH OPERATION

BLACK

BLACK

PURPLE

CANOPY SWITCH

LINE VOLTS

YELLOW MUST BE CONNECTEDTO BOTTOM TERMINAL WITHSWITCH IN POSITION SHOWN

START - X & Y CLOSED Z OPENRUN - X & Y OPEN Z CLOSED

RED

RED

HI

WHITE

CAPACITOR

START

YELLOW

LOW

YELLOW

HI-LOW SWITCH

PURPLE

REMOVE BOTH YELLOW LEADSFROM ‘A’ TERMINALAND CONNECTTO TERMINALL1.

REMOVE BLACK LEAD FROM HI-LOWSWITCH AND CONNECT IT TOTERMINALA.

LEAVE SWITCH IN CANOPYANDLEAVE PURPLE LEAD CONNECTEDTO SWITCH.

CONNECT POWER SUPPLY LINES TOTERMINALBOARD

L2-L1 HIGH SPEEDL2-A LOW SPEED

BEFORE REPLACING MOTORCANOPY, BE SURE ALLLEADS AREPROPERLY PLACED TO PREVENTDAMAGE FROM GOVERNOR AND/ORCANOPY.

NOTE: Several different connections have been used in production. If the wiring on themotor you are reconnecting does not match these diagrams contact A.O. Smith andwe will FAX or mail a connection for that model.

Page 48: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

46 Pump Motors

Level 2 A.O.Smith

PURPLE

SWITCH BOX

BLACK TRACER

YELLOW

COMMON

DISCONNECT PURPLE AND YELLOWLEADS FROM HI-LOW SWITCH ANDCONNECT TOGETHER.

DISCONNECT BLACK TRACER LEADFROM HI-LOW SWITCH PERMANENT-LY. TAPE UPEXPOSED END.

CONNECT POWER SUPPLY LINES TOTERMINALBOARD

L2-L1 HIGH SPEEDL2-A LOW SPEED

2-SPEED MOTORS — HIGH SPEED START SCHEMATICDIAGRAMS AND RECONNECTION INSTRUCTIONS FOR

REMOTE OPERATION2-Speed with Hi - Low Switch

Mounted in External Box

START

BLACK

CAPACITOR

YELLOW

RECONNECTION FOR REMOTE SWITCH OPERATION

L2

L1

B

A

NOTE: Several different connections have been used in production. If the wiring on themotor you are reconnecting does not match these diagrams contact A.O. Smith andwe will FAX or mail a connection for that model.

Page 49: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

Pump Motors 47

Level 2 A.O.Smith

MOTOR REPLACEMENT REMINDERS

A. If possible, isolate the cause of failure so that:1. There will be confidence that a similar

replacement motor will have an accept-able service life.

2. If external conditions (moisture, low volt-age, etc.) contributed to the failure, theymay be corrected.

B. Match the mechanical and electrical charac-teristics of the original and replacementmotors.1. Mounting

This will include the end frame, shaftextension and base (if so equipped). Thenameplate will provide some or all of theneeded information in the section forframe size (FR).

2. ElectricalDetermine operating voltage, phase, maxamps and hertz or cycles.

3. HorsepowerMultiply nameplate horsepower times theservice factor to find total horsepower.The total horsepower of the replacementmotor must equal or exceed the originalmotor.

4. Model NumberEach motor has a series of numbersand/or letters which designate one specif-ic design. This number alone is sufficientfor the manufacturer to cross referencethe motor for replacement. If this num-ber was crossed previously, it may be on apublished list. Don't rely on the numberalone. A difference of one number or let-ter means a different motor. The modelnumber may contain some descriptiveinformation, but by itself does not enablesomeone in the field to select a replace-ment.

MotorReplacementReminder s

Page 50: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

48 Pump Motors

Level 2 A.O.Smith

It may even lead to confusion. For exam-ple, some A.O. Smith pump motor modelnumbers begin with a letter: C =Capacitor Start, S = Split Phase, K =Capacitor Start and Run, P = Polyphase.The next two numbers designate themotor frame size: 48 = 48 Frame, 56 = 56Frame. The next letter designates horse-power: J = 1/2, K = 3/4, L = 1, etc. Theframe in the model number refers to themotor's diameter of 5-5/8", not the NEMAframe designation which may be 56C or56J, etc. The horsepower letter designa-tion is useless without the service factor.

If the nameplate is not legible, it will benecessary to utilize pump data and sys-tem voltage in order to select a replace-ment.

C. Always install a new seal when reassemblinga pump or installing a replacement motor.

D. Be sure the motor is connected for the systemvoltage. Most A.O. Smith dual voltage pumpmotors are factory connected for the highervoltage for two reasons. First, lower currentdraw on high voltage allows the use of small-er circuit wire, and reduces light flicker ordimming when the motor starts. Second, if amotor is connected for high voltage and lowvoltage is applied, the motor will just hum, orstart and run very slowly until it trips theoverload. If a motor is connected for low volt-age and high voltage is applied, the motorburns out immediately.

E. Always be sure the motor is properly ground-ed before applying power.

F. Use an ammeter to assure that the motor isnot overloaded. The max load or SF (servicefactor) amps on the nameplate should not beexceeded.

Page 51: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

Pump Motors 49

Level 2 A.O.Smith

OPERATING REMINDERS

A. Locate the pump/motor in a clean, dust-freearea. Most pool and jet pump motors areopen drip proof designs which circulate exter-nal air for cooling. Air contaminants such assweeping dust and grass clippings may cloginternal air passages leading to overheating.

B. Protect from excess moisture. Don't hosedown the area around the motor when it isrunning. Elevate the pump/motor if it is inan area that is prone to flooding.

C. If an external motor cover is used, be certainit does not trap moisture or allow cooling airto recirculate.

D. Don't store or use chemicals close to themotor.

E. A running motor that is too hot to touch isnot necessarily overloaded. Class B motorshave a maximum operating temperature of130˚ centigrade (266˚ F).

F. If pool or jet pump motors are removed fromservice at the end of a season, do not wrapthem tightly in plastic. Temperature changesmay cause condensation with detrimentaleffects.

G. Thinner air at higher altitudes has less cool-ing ability. As a rule of thumb, the next high-er horsepower rating may be used at alti-tudes above 3300 feet to compensate.

OperatingReminder s

Page 52: A.O. SMITH MOTORS · a.o.smith application motor master y university includes: swimming pools sp a & jetted tub jet pumps installation tips repair troubleshooting other modules include:

531 NORTH FOURTH STREETTIPP CITY, OH 45371

937) 667-6800FAX: (937) 667-5873

www.aosmithmotors.com

© 2001 A.O. Smith Corporation Bulletin #3300 3/01