P13472 CHANGE OF RESISTANCE TEST

STAND

DETAILED DESIGN REVIEW PACKET

FEBRUARY 20, 2013

FACULTY GUIDE:DR. BENJAMIN VARELA

TEAM MEMBERS:JACOB LENNOX

COLIN PAYNE-ROGERS

Detailed Design Review Agenda

Meeting Purpose: To review experimental interface relay circuit design, proof-of-concept experimental results, actual interface relay circuit design, bill-of-materials, risk assessment and MSD II test plan

Review Materials: Detailed Design Review Packet (this document)

Meeting Date: February 20, 2013

Meeting Location: Cooper Crouse-Hinds

Meeting Time: 11:30AM

Meeting TimelineTopic Page (this packet) Required Attendees

Customer Specifications 2-4 EveryoneProof-of-Concept Circuit Design, Hardware

4-7 Everyone

Proof-of-Concept Experimental Results

8-9 Everyone

Relay Circuit Design 9-10 EveryoneBill of Materials 11 EveryoneTest Plan 12 Everyone

Customer Specifications/Needs

The following table was created using a template file available from the Senior Design MyCourses. Importance of “1” means it is a must-have specification.

Cust. Need #

Impor-tance Description Comments/Status

CN1 1

Measure the temperature using the change-of-resitance (linear regression) method, per UL844 standard.

The data will be stored in excel-compatable files and a macro will be written for data reduction to be done on the same computer, but not by LabView (so that a cheaper version of the LabView

software can be used on the test stand)

CN2 1 Design and build the interface relay circuit.

The interface relay circuit has been designed, a preliminary proof-of-concept experiment has been performed to demonstrate the

veracity of the circuit, the design and experimental results will be presented to the customer at the detailed design review. It should be noted that there are components to the relay circuit that are not

included in the design yet (capacitor in/out, to ballast, to lamp, from balast, etc...see Cooper circuit design).

CN3 1 Select and purchase a multimeter capable of

A multimeter has been selected that is interfaceable with LabView (it is a National Instruments multimeter) and has the required

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reading coil resistance with a resolution of 0.01 Ohms.

resolution. The multimeter is capable of taking 4-wire resistance measurements and is compatable with the PXI Chassis used in

the design (???).

CN4 1 The multimeter must be able to be calibrated.

The current plan to achieve this customer need is to include in the final design a resistor of known resistance that is always

connected to one channel of the NI switch. The resistance of this resistor will be tested with various multimeters to ensure its

resistance is known, and the LabView program will include the ability to measure this resistance, show the difference between the known value and the measurement, and calibrate the instrument

(hopefully there is a command in LabView to calibrate their multimeter).

CN5 1

Incorporate a thermocouple to measure the ambient temperature of the ballast core.

Along with the NI PXI system (multimeter, switch) a multi-function DAQ will be purchased as well. This DAQ had digital

inputs/outputs and will be capable of taking readings from the thermocouple (that will also be purchased from NI?).

CN6 1The LabView program will be able to measure the resistance of up to 6 coils.

A LabView "switch" (16 or 32 channel) will be incorporated into the final design that can be controlled from LabView to take the

measurements of any combination of coils. The program will be written with a user-friendly interface that will allow for the operator

to choose which coils need to be measured.

CN7 1The first "stabilized" measurement should be taken within 5 seconds.

The response time of all of the LabView equipment is fast enough that we should have no problem achieving this. The "power

circuit" switches have a delay when being turned off, but we can account for this in the LabView programming so that the National Instruments hardware never comes into contact with the voltage

from the ballast.

CN8 1 Readings must be taken one at a time.

The capability of the LabView switch to change channels at a high frequency should take care of this. There is a chance that the

LabView program will have to "delegate" a certain amount of time for each 4-wire measurement so that the multimeter has time to

stabilize before the next measurement is going to be taken.

CN9 1A minimum of 40 readings must be completed in 30 seconds.

As stated above, the speed at which all of the National Instruments hardware is capable of switching and operating at

should make this requirement very easy to achieve. It is likely that about a half a second will be delegated to each reading, which will hopefully be enough time for the multimeter to read the resistance

of the coil before the switch changes coils.

CN10 1Allow the operator to test all of the coils or any combination of coils.

This will be achieved in the LabView programming. Each channel (or set of channels) in the NI switch will be designated to a certain

coil. The channels that will be used during each test will be chosen by operator. OR, all channels will be used in each test but the channels that will be output to the excel file for data reduction

will be chosen by the operator.

CN11 1

Make a plot of resistance versus time for each coil, make a linear regression of this plot and calculate the temperature of the coil.

This will be done using a macro in excel. It may be possible to incorporate the macro into a BAT file that the operator can run

from the desktop and use to choose which files contain the data that needs to be reduce. How this data reduction works depends on how much Cooper trusts its operators to use the excel macro

(or the engineers?).

CN12 1Store the data in up to 9 different portable-format files.

Although the LabView program has not been written yet, it is assumed that the number and types of files that the program

outputs can be incorporated into the LabView program relatively easily.

CN13 1

Operator can input date, time, coil material…program has the following functions: pre-run test, run auto-test, view results, print results, terminate.

Achieve via LabView interface, most likely the interface will be more customizable than this to achieve some of the above

customer needs.

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CN14 1Test stand must be contained within a rolling enclosure.

This enclosure will be designed at the beginning of MSD II…it will use some form of aluminum bracket and plywood and what-not…once the LabView parts and laptop are on hand the dimensions

and specs of the cart can be determined.

CN15 1

The interface relay circuit must operate within the ballast operating range 120-480VAC, 30-40Hz.

With the power circuit and the measurement circuits separated by relays controlled by LabView, this customer need is satisfied by

ensuring the electromechanical relays are rated to operate at the correct voltage, which they are.

Cust. Need #: enables cross-referencing (traceability) with specificationsImportance: Sample scale (1=must have, 2=nice to have, 3=preference only), or see Ulrich exhibit 4-8.

Experimental Circuit Design, Hardware

The following pages detail the conceptual experimental design and images of the hardware setup used during the experiment. The goal of the experiment was to show that two separate (in this case manually operated) control circuits could be used to provide three instances of operation:

1. Off – No power to the ballast, no measurements being taken with the Multimeter2. Power – Supplying the ballast with power, severing the connections between the

ballast and the Multimeter so the measurement hardware is not damaged during ballast operation

3. Measure – Cut off power to the ballast and restore the connections between the ballast coils and the Multimeter so the 4-wire resistance measurements can be taken

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Figure 1: Proof-of-Concept Experimental Circuit Design5

Figure 2: An overview of the experimental setup, digital Multimeter and ballast both connected.

Figure 3: Close-up of the “relay circuit(s)”, power supplies (right), measurement control circuit (left, top), power control circuit (left, bottom).

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Figure 4: Close-up of the measurement control circuit, wiring used to achieve parallel connections to the relays (so that each sees 24VDC).

Figure 5: Close-up of the power control circuit, two terminal blocks used as junctions between the ballast connections (com, 120VAC to ballast), the measurement connections (to Multimeter) and supply connections.

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Experimental Circuit Design, Results

In addition to the typical ballast testing (4-hours of ballast operation followed by the initial temperature calculation) an additional test was performed to ensure that the experimental circuit was not offsetting the resistance measurements. Coil 1 and Coil 2 resistance measurements were taken by connecting the 4-wire measurement leads from the ballast directly to the Multimeter and then compared to measurements taking by connecting the ballast to the experimental apparatus and taking resistance measurements through the apparatus. The following table summarizes these results (note that the difference between the values is an order of magnitude lower than the required measurement resolution in the PRP, and that the difference is not consistent from coil to coil):

Coil 1 Resistance (Ω) Coil 2 Resistance (Ω)Direct-to-Ballast 3.798 2.678Through Relay Circuit 3.801 2.677

Figure 7: Room Temperature measurements taken at RIT.

Using the experimental setup detailed above, the following “4-hour” results were obtained (blue) and compared to the results provided by Cooper Crouse-Hinds (red, see table).

Figure 6: Comparison between test data received from Cooper and the experimental test performed at RIT.

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Initial temperature calculations:Rc from DMM

not from DMM

Coop

er Rc (Ω) 4.1 3.66Th (°C) 51.75 86.52Rh (Ω) 4.57 4.57

RIT

Rc (Ω) 3.801 3.361Th (°C) 55.92 93.94Rh (Ω) 4.3037 4.3037

Figure 7: Tabulated calculations.

There are a few possible reasons why the data gathered at RIT is different from the data gathered at Cooper:

The ballast was operating without the lamp attached at the RIT test. This may change the temperature as well as internal ballast operating conditions.

The ambient temperature for ballast operation was different in each case. The size of the room in which the experiment took place was much larger at RIT. The only wires of the ballast connected to anything during the test were the

common and 120VAC wires. The capacitor, or any other wire, were not connected. The voltage being supplied to the ballast may have been different.

Relay Circuit Design

The prototype change-of-resistance test stand design proposed below is based heavily on the concept used to design the experiment above. Three “circuits” will control the operation and testing of the ballast. The first circuit, the “power circuit” will supply the ballast with power (when engaged) and allow for a method to cut power from the ballast separately from the method used to being taking resistance measurements. This circuit is in place to ensure the hardware does not “see” high voltages being supplied to the ballast. The second circuit, the “measurement circuit” is similar to the power circuit in that it is in place as a “gap” between the ballast/power circuit and the Multimeter. This circuit will “engage” only after the power circuit is disengaged, and only then can measurements begin. The third circuit consists of the National Instruments (NI) switch and Multimeter. This hardware is controlled by LabView and lies in the NI “PXI Chassis”. This circuit is responsible for switching from resistance measurement to resistance measurement during the data acquisition period of ballast testing (and only after the power circuit has disengaged and the measurement circuit has engaged). The NI PXI Chassis will also include a multi-function DAQ that will allow LabView to control the power circuit and measurement circuit. This DAQ can also take measurements from the required thermocouple. The hardware required to design and build this circuit is outlined on page 9 of the packet.

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Figure 9: Basic concept design for the relay circuit, with major hardware10

Bill of Materials

Accessory Vendor PN Description Indv. Cost Quantity CostPXI Chassis NI 781162-01 NI PXIe-1073 $ 1,499.00 1 $ 1,499.00

Chassis Power Cord NI 763000-01 $ 9.00 1 $ 9.00DMM NI 780011-01 NI PXI-4065 $ 1,499.00 1 $ 1,499.00

Relay Module NI 778572-66 NI PXI-2566 $ 1,080.00 1 $ 1,080.00

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Relay Terminal Block NI 778717-66 TB-2666 $ 277.00 1 $ 277.00

System Assurance NI 960903-02 $ 310.00 1 $ 310.00

Power Circuit RelayMcMaster Carr 7230K91 4PST $ 76.91 4 $ 307.64

Power Circuit Relay Allied Elec 70198625 DPST $ 10.07 1 $ 10.07

USB DAQ NI 779051-01 USB-6008 $ 169.00 1 $ 169.00

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Circuit Total $ 5,160.71Labtop $ 500.00 1 $ 500.00Labview Lisence NI $ 999.00 1 $ 999.00Miscellaneous Cart etc. $ 1,000.00 1 $ 1,000.00

*Highlighted Boxes are approximate costs Total $ 7,659.71

Test Plan

The following test plan was created using a test plan template document available on MyCourses and then copied from excel:

Number Description

1

Test the ballast temperature/resistance measurements with a borrowed 4-wire multimeter but the updated relay circuit (using "final hardware" and one coil rather than "experimental hardware"). Show the exponential decay, and the difference in resistance measurements when measuring the ballast directly and through the circuit.

2

Test the ability to switch between different coil measurements using the NI switch, manually and automatically, and then verify the results from test #1 for the same coil when switching to the other coils inbetween each measurement (possibly taking all coil measurements)...with the borrowed multimeter still?

3

Show that initial measurements are capable of being taken within 5 seconds, and that all 6 coil measurements are capable of being taken at the required rate. This would be a final "proof-of-concept" test, showing that the LabView program can be used to measure 6 coils as quickly as needed and can spit out the correct data (data compared to #1). The NI multimeter used this time to show that it is calibrated as well as the borrowed multimeter.

4

Test the calibration routine by using a "correct" and "incorrect" calibration. The "correct" calibration for the routine should give the correct ballast (room temperature) results while the "incorrect" calibration should offset the ballast resistance measurements? This test depends on the final method for calibration.

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Timeline

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