moving more than motors

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Analysis and developement of drivesfor machine and system builders.

W. Esser

Technical Essay

Moving More than Motors

SystemsIndustrial AutomationBuilding Automationtra Combinations

Think future. Switch to green.



Over recent years, the Moeller Company

Group has been working, at first only

internally, on a Company philosophy

focusing on what will happen in the future,

under the working title “Competency with

motors gets more moving“. Now we

want to go public with it.

This essay is intended to introduce the

Moeller campaign “Moving More than

Motors“ and, as a first step into this topic,

to point out fundamental trends concer-

ning electrical drives, their automation and

the associated protection technology. It will

prove how thoroughly Moeller has sought

to find out the diverse requirements of

users in the various branches of industry,

also the differing peculiarities and traditi-

ons in Europe were investigated.

Thus the product assumes secondary

importance within the value creation chain

in favour of the solution. Motor applicationsolutions and motor application expertise

are the logical steps in development from

the Moeller slogan “More than Products“.

The design specifications for the new

generations of products were to include the

question at every stape“... and what

benefit does it bring for the customer?“

Moeller will in future signpost contribu-

tions concerning the automation of drives

generally at every opportunity with the

special symbol (Fig. 1). New products and

product systems representing the reaction

to the trends described will be introducedas they appear, in a series of separate

articles. During their market launch, they

will be identified each by their own unique

symbol (Fig. 1) as belonging to the overall

campaign “Moving More than Motors“.

What does Moeller mean by

“Moving More than Motors“Moeller and Felten & Guilleaume, in over

100 years and over 125 years corporate

history respectively, have proven the

Group’s competency in the switching and

protection of motors. Indeed, with the

legendary PKZ, for example, they set the

standard. The Type PKZ nowadays is

synonymous with motor-protective

circuit-breaker. In tune with the technical

progress of power electronics, electronic

products for controlling and regulating

motor speed were added to the purely

electromechanical ones, and this rangenow represents a sucessful highly area of

business.

By integrating Felten & Guilleaume,

Moeller has added to its own know-how

portfolio the expertise to develop and

produce particularly high-specification

electric motors. These explosion-proof

low- and medium-voltage motors have a

large market share in the chemical

industry, as well as the petrochemical and

off-shore sectors, where the highest

degree of safety and reliability are

mandatory.

“Moving more than motors“ concerns the

complex processes involved in drives and

all their facets. We are aware that, before

Moeller can sell a single switching or

protective device for a drive, a motor has

to be sold first. Before the motor can be

sold, there has to be an order for a

machine or system. This is why we

describe the electric motor and the

machine as partner products to our own

products. In other words, we need to look

at optimize the value creation chain as awhole.

Studies of development tendencies to do

with motors, processing machinery and

systems [1, 2] had to be carried out in

preparation for the strategic planning of

new product systems for electro-

mechanical and electronic switching and

protective devices, and for an automation

strategy. We asked ourselves: “What is

going to change regarding our partner

products in the next few years?“

Interesting questions for example, were:

• Will motor protection be incorporated

into the motor

• What about the development of the

motor currents

• What will be the development trend

of AC and DC drives

• Will there be new kinds of motor

• Are the switching conditions

changing

• What is the relationship between the

Standards situation and practical

engineering

• Are user habits changing

• What is the future development

going to be regarding the networking

of electrical operating media?

We intend to answer these questions by

charting the trends, but mainly with

specific, new products and application

solutions. It was important to analyze

which drive and automation applications

were being used in which branches of

industry and which functions were

necessary for these applications [3].Table 1 shows some of the applications

investigated and the corresponding

functions to illustrate and clarify theabstract terms used. Table 2 lists more

specific drive functions.

2

Moving More than MotorsAnalysis and development of drives for machine and system builders.Dipl.-Ing. Wolfgang Esser

Fig. 1: Moeller intends to use this logo tosignal specialist publications with thetheme “Moving more than motors”

Fig. 2: Moeller intends to use this logo tosignal clearly that products andproduct systems belong to thecampaign with the theme “Movingmore than motors“

Knowing what the requirements of the future will be, enables us to find solutions for todayUsing tested and proven applications reduces your risk, and saves you time and money. With our well-founded

technical expertise we minimize interfaces, finding single-source solutions, optimally tailored to your requirements. Whatis more, we always have the future in mind, technically as well as in economic terms. After all, switching, protecting andcontrolling motors has been a Moeller core competency for more than a century. We are aware of the trends, we knowhow to use motors, and this gives us the expertise to implement advantageous solutions for all kinds of machinery. Andwe do this right across the industrial spectrum, throughout the world. For the stand-alone machine, and up to highlydynamic multi-motor installations – we are your partners.

Moving More

than Motors

Moving More

than Motors



The evaluation of these studies provided a

comprehensive picture of the

requirements in the sectors under review,

and enabled us to define our target

sectors whose requirements in terms of

automation and systems business were

going to be covered to a particularly high

degree by the planned Moeller product

range. By proceeding in this way, we can

work effectively together with our

customers and offer them not only the

necessary Moeller products, but also the

associated application know-how and

application solutions via our solution-

oriented System Sales operation with its

specialists for the various branches of

industry. Defining our target sectors for

the automation and systems business does

not mean, of course, that we cannot

supply other sectors with components via

our dedicated distribution channels.

We started the above studies after talking

to the technology leaders in machine and

systems building within the various

sectors, and with important motor

manufacturers, because we expected

them to have the clearest view of future

developments. And this proved to be the

case. Later, we needed to make sure that

the results of these technical discussions

were not just relevant to a few exclusive,

high technology products, but also to thevolume business. End users of drives were

asked what they felt were weaknesses of

today’s products and systems, and what

they expected of the future. Moeller

employees participate in many cross-

sector working parties concerned with the

future of drives powered by electric

motors, both at national as well as

international level.

We feared that we would collect a great

deal of unrelated individual pieces of

information that would not lendthemselves to be collated into one

uniform picture of the future. But even

after just a few discussions we found that

the core statements and core problems

agreed totally. The great topic of

“decentralization“ ran through all the

discussions like a thread. Although for

differing reasons. The on-going

mechanical modularization must be

followed by electrical modularization. Due

to the fact that central switching cabinets

are being dispersed in this way and smaller

switching panel modules are being

physically separated, the word used isdecentralization. Some of the outcomes of

these studies have meanwhile found

confirmation in market developments.

3

Automation applicationsin selected branches

of industry

Automation functionsin selected branches

of industry

Table 1Overview of some investigated applications that are necessary for the automation of selectedbranches of industry; also an overview of selected functions required for these applications. Thealignment of branches with applications and functions was to help work out an automation strategyand for definition of our target segments.

Table 2: Overview of selected functions required in variable speed control systems

Functions for drives

Pumping Control

Switching On and OffReversingBrakingStarting Starting – delta

Soft startingVarying the speed Multi-speed switching

Control: steplesslyRegulation: individual / synchronization

4 quadrant operation Positioning / adjusting the positionMotor protection: centralized/ decentralized

Explosion protection

Pumps ControlFans Regulation

Conveyors Piece goods Arithmetics

Bulk material Visualization

Mechanical Driving

mixture Positioning

Gasses / liquids Recipe management

Sieving Communication

Weighing Operation

Mixing Measuring

Dosing By weight Monitoring

By volume Documentation

Sequence controlPlant control

Slide control / valves

Air conditioning

Heaters / dryers

Coolers

Milling

Electric/hydraulic/pneumaticpiston actuation

Press control

Separators / filters

Positioning controls

Identification systems

Light-barrier control

Measuring systems

Safety circuits

Regulation

Diagnostics



The whole area of drives is at present

going through a highly dynamic phase

that is strongly interacting with the very

core areas of Moeller Company Group

business. New solutions in the switching

and protective device field enable new

solutions to be found for drives, such as

the money-saving decentralization of

drives, with a completely new convenience

of operation and remote diagnosis, or the

wear-reducing method of running up

motors using softstarters [4]. On the other

hand, new objectives for machine and

system builders demand further

development of switching and protective

devices to achieve higher operational and

short-circuit switching capacities. New

pieces in the solutions mosaic allow new

configurations. The various disciplines

involved stimulate one another positively.

In summary, “Moving more than motors“

in Moeller terminology means effectively

to take into account and promote drives,

even beyond the company’s own areas of

business.

One major area of application for electro-

mechanical and electronic switching and

protective devices lies in the ever more

sophisticated control and regulation of

electric motors. Since the restructuring of

the Group of Companies, this work is

being dealt with mainly by Moeller

Industrieautomation GmbH.

Developmenttrend – motors

A few examples of changes in the partner

product “Motors“ are listed below [5]:

• Trend towards smaller motors

Even today, 95% of all three-phase

motors have a rating of < 7.5 kW, and

80% an even lower one at < 4 kW. The

cost-efficient possibilities of electronic

synchronization controls enable large

motors, previously driven for example

via line shafts, to be substituted by a

number of smaller motors. Mechanical

problems are eliminated and modular

systems promoted. Since operating

media prices are dropping, but payroll

costs are rising, any ancillary processing

steps are being automated. These tasks

usually only require small motor

ratings.

Motors rated > 75 kW represent

approximately 0.3% of production.

However, it is noticeable that the

ratings required of large LV three-phase

motors are tending to be even higher

and moving in the direction of 750 kW.

• Changes in the construction

of motorsMotor statistics show that the trend is

towards motors being built as

complete machines, e.g. as pumps or

fans, since they tend to appear in the

statistics of such finished products

instead of those of motors. Motor

manufacturers have confirmed this

trend.

Machine tools are increasingly being

driven directly, the chuck of a lathe, for

example, being mounted directly on

the motor shaft. This does away with

the need for gears and the noises

associated with them or with V-belts.The efficiency of the motor is improved

and it no longer has to have its own

enclosure but is included in that of the

machine.

• Evolution in the function of the

electric motor

When it was first developed, the motor

was designed to relieve man and beast

from hard labour. It was intended at

first to rotate and move something.

Nowadays, this is no longer enough,

the motor having become in manycases a tool in its own right. Often, it

can influence the quality of the

products. But even this sometimes is

not enough and then the interrelation

of several drives has to be tuned in

order for them together to define the

quality of the product. The

requirements of switching frequency

and the dynamics of the regulating

system are completely different now

than on the early motors that

constantly drove just one transmission.

Examples of this development can be

shown in the consistent quality in pipeor glass-fibre drawing machines, or in

multi-colour web-printing.

• Trend towards variable-speed

motors

The rotational speed of a motor

(motors) must be variable in order to

allow it to play its role in determining

product quality. Step-by-step speed

adjustment, even using electro-

mechanical switchgear is not gone, and

suffices for many production processes.

Where continuous adjustment isrequired, it can in many cases be

effected using electronic actuators or

regulators. The terrific development of

three-phase frequency inverters is not

only pushing aside the previously more

favourable DC drives and meeting

present expectations better, but will

certainly generate new automation

demands and bring about new

methods and procedures. The

economic benefit is of course that

these frequency inverters can be used

with standard motors. Variable-speed

motors also open up interesting

perspectives in terms of energy

consumption. Such motors often allow

considerable energy savings to be

achieved, e.g. by varying the flow rate

in heating installations. In 4-quadrant

operation it is even possible to reuse

the braking power.

The availability of vector-controlled

frequency inverters banishes DC drives

to applications in the higher ratingrange. But DC technology is being

made more attractive too by the

parallel development of brush-less DC

motors. The competition between the

two systems, AC and DC, is partially

responsible for motor manufacturers

having mostly specialized on

production of either three-phase or

direct-current machines, both groups

being anxious to secure their own

continued existence.

• Proportional increase in the use ofhighly dynamic servomotors

The usual speeds of 1500 or 3000 rpm

in 50 Hz systems are no longer

sufficient for many applications. In fact,

for certain processes, speeds of 6000 to

12000 rpm are to be regarded as

normal, whereas high-speed

processing machines even work with

speeds of up to 180 000 rpm. The latter

operate with supply voltages ranging in

frequency up to 3000 Hz. It is quite

normal nowadays for machine controls

involving busbars to be equipped for

various or variable frequencies as high

as the kHz range. The speed of the

modules involved in the process is

adjusted via a change in frequency to

suit the material to be worked.

In addition to the absolute speed, it is

particularly the dynamics and the

control range that are of critical

importance, but also the possibility of

achieving torque even at zero speed.

Servomotors have been found to be the

answer for such complex and

demanding applications.

Although in a ‘normal’ drive situation,

it is perfectly acceptable for motor and

control device to be of different

4



manufacture, where servomotors are

concerned, motor and control unit

usually come from the same source. In

such drives, conventional motor-

protective devices are totally replaced

by control electronics.

Such highly dynamic drives by now

represent a considerable proportion of

the total.

However, it appears that the new

vector-controlled frequency inverters

are in the process of winning back a

portion of the dynamic applications in

favour of the conventional three-phase

squirrel-cage motor, since servomotors

are being used in some applications

that do not really need them.

Fall-out from the EUMachine Directiveand EU EMCDirective

Certain problems with frequency inverters

became known and were investigated in

conjunction with the introduction of the

CE mark and the European Directives on

Machines and on EMC. Due to their

switching speeds of < 250 µs, frequency

inverters incorporating the fast IGBTs1 lead

to voltage variation speeds du / dt in

excess of 2.5 kV / µs. Where cables

between inverter and motor are longer

than 10 to 20 metres, travelling waves may

arise in the conductors, with the

frequency increasing with distance up to

250 kHz. What is more, such travellingwaves represent a continuous load rather

than a transient one, and run on into the

motor where they destroy the first of the

series-connected windings.

It may be that these effects will lead to

changes in the Standards governing

motors in installations subject to explosion

hazards. Since it is mandatory for the

frequency inverter in EEx(e) installations to

be located in the non-hazardous area, the

cable lengths involved in such applications

are often quite extensive and subject to

the problems described. Nor have suchloads ever been considered in conjunction

with switchgear.

On the one hand, Moeller supplies choke

coils in order to protect motors against the

risks described. On the other hand, and for

the same purpose, motor manufacturers

are combining motor and frequency

inverter into one unit to avoid the long

cables. This brings the frequency inverter

into the same high-risk environment with

high temperature, dirt, vibration, cooling

water and drilling oil. Another factor that

restricts the freedom of such a

combination is that having to cool it

reduces its output. Moeller recommends

physical decentralization of the switching

installation. This means removing the

frequency inverter from the central

control panel and locating it at a

reasonably close proximity to the motor.

The high heat loss within a central panel

possibly containing several frequency

inverters is another factor in favour of

decentralization.

Other consequences of the high voltage

variation speeds are ripple voltages that

induce currents strong enough to break

through the grease in ball bearings and

cause chatter marks and the eventual

failure of the bearing. Nowadays insulated

ball bearings are sometimes used.

Travelling waves cause more than normal

wear on the internal insulation of the

motor. The above effects, together with

the travelling waves have led to specialmotors for operation with frequency

inverters that include IGBTs being

marketed. Standard motors must be

insulated to Class F.

Motor protectionconcepts

There is broad agreement regarding the

statement that the motor-protective

functions available today are entirely

sufficient for all the volume applications.

This applies to electromechanical

motor-protective circuit-breakers and

motor-protective relays as well as to the

electronic solutions. Today’s medium-

priced electronic relays combine the two

available methods, indirect temperature

monitoring via the current and direct

temperature monitoring by means of

thermistors in the motor winding [6]. The

protective function using thermistors hasrisen in importance with the number of

variable-speed drives, due to the danger

of excessive temperature rise because of

restricted ventilation. In addition, for

economic reasons, motors are no longer

selected with the same reserves as

previously.

The conventional motor-protective

circuit-breaker that ensures separation in

all poles and at the same time provides

short-circuit protection also for cables andwiring, is still in pole position as far as

motor protection is concerned, at least

with non-regulated motors.

The overwhelming majority of motor

failures, more than 80%, is due to

mechanical faults and not to factors that

have anything to do with the electrics.

Damage to bearings is the main cause of

failure, another considerable one is

damage to the gears. Thermal motor-

protective devices cannot protect against

these.

It is noticeable that machine

manufacturers would rather not provide

general motor protection as stipulated by

IEC/EN 60 204, probably for reasons of

current economic pressures. Failure rates

are regarded as negligible. However, it

should be noted that most of the

protective devices used these days provide

the indispensable cable and wiring

protection as well. The absence of motor-

protective elements would also run

counter to the increasing demand for

targeted (remote) diagnostic options.

Evolutionof machineconstruction

Modern machines are increasingly

developed and built as modular systems in

order to allow the range of variants to

become economically viable andmanageable. In some branches of industry,

certain processing steps are needed

repeatedly one after the other, which also

means that several of the same modules

are required. Such requirements can

multiply considering whole installations.

Modular machine construction (building

block principle) provides an elegant

solution for the assembly and transport

problems involved.

It reduces the manufacturing time for the

mechanical hardware, and allows

individual customer wishes to be more

easily meet. Matching to differing national

regulations, traditions and competitive

situations is made much easier, as is

changeover from one processing material

or recipe to another.

5

1 IGBT = Insulated Gate Bipolar Transistor



The electrics for these modular machines

however, are mostly still built separately as

a complete unit for the whole machine or

installation and engineered separately in

one large, central control panel. Customer

wishes on the other hand are clearly

tending towards having the electrical

portion of each mechanical module either

attached to, or at least spatially and

functionally aligned with it. In other

words, the customer wants to be able to

take the mechanical module off the shelf

and thus have the matching electrics in his

hand at the same time. This evolutionary

step in effect modularizes the electrics too,

and simplifies the up-dating or

enhancement of existing plant while mini-

mizing time requirement and risk invol-

ved.

Evolution ofmachine controlsystems

The importance of the electric motor at

the machine or in the production plant has

grown in recent years, and as described in

previous paragraphs, is going to continue

to increase.

The requirement of the electrical

equipment as a whole has expanded.

An examination of the evolution of

machine control systems (electrical

equipment) shows that on the first,

simple, electrically equipped machines,

the switchgear was located directly on the

machine or in the machine housing

(Fig.3).

It consisted mainly of mains switching

devices. On this type of machine, due to

the clear layout, there was rarely a need

for command and signalling devices, and

logic devices were not needed at all.

This situation still prevails today on such

simple machines.

As machines became more complex and

the relationship between various drives

had to be taken into account, as well as

variable operational steps becomingpossible, the electrical equipment was

combined in order to reduce the effort

and material required for the interlock

wiring to a minimum (wiring-oriented,

control systems). Even the first electronic

control systems were wiring-oriented with

their programs hardwired. With increasingequipment complexity, central control

panels came to be built because of the

growing necessity to keep all the

switchgear as closely together as possible

for the interlock wiring links and for

clarity of layout for the purposes of

maintenance. This solution still forms the

overwhelming majority of control systems

for relatively complex machinery or plant

(Fig.4, Fig.5).

Only the development and introduction ofbus systems for service installation and

control functions removed the constraints

of having to centralize the switchgear for

the purposes of sequence and interlock

wiring. Signalling and diagnostic functions

were considerably improved and

simplified in this way. Switching andprotective devices can now be

decentralized and located directly at the

machine or in the installation.

6

Fig. 3: One-motor machine with a minimum ofswitchgear involved. No logic links

necessary.

Fig.4: Simple multi-motor machine with little interdependence between its drives.

M1 M2 M3 M4 M5 M6 M7 M8

Fig.5: Complex multi-motor machine with highly dynamic interdependence between some of itsdrives, and constructed in today’s layout, with large, central switching cabinets. Controldesks, control cabinets and power sections are physically partially separate. Motors, localcontrol circuit devices, sensors and safety components individually cabled to the controlpanel. Some control circuits are wired in multi-core cables from wiring nodes. These multi-core cables are increasingly being replaced by bus systems today.



The next and inevitable evolutionary step

in control engineering is to run a power

bus alongside the machine or installation

in addition to the data bus (Fig.6). This

solution is already increasingly being used

in practice today. Of course, it enables the

operational switching device, e.g. the

motor-starter consisting of contactor and

overload relay or motor-protective

circuit-breaker, or the frequency inverter,

to be located where it ought to be,

namely close to the operating medium it is

intended to switch. By taking this step,

one dispenses with the central control

panel and replaces it by several intelligent

tap-off units on a three-phase bus system.

It is not such a big evolutionary step from

networkable switchgear in a control

cabinet to networked, distributed devices.

The only extra requirements are for

switchgear housings and terminations

that meet the high ingress protection

degrees IP65 or IP67 necessary at the

machine, against oil, cooling water, dirt

and unfavourable temperatures. Data and

power bus systems then link the individual

modular control and power sections.

As a spin-off from this step in evolution,

the trend towards plugging in the links

between functional units and using

prefabricated cables where possible is

becoming a reality. Wiring errors are ofcourse drastically reduced by the use of

plugs and pre-tested cables. The initial

cost of prefabricated cables with plugs

may appear high, but value analysis shows

that so is the benefit of such equipment. It

reduces the onus on installation personnel

or takes into account the level of expertise

present in the local personnel. After all,

connecting to terminals is a job for a

trained fitter, while plugs can be used by

anyone.

Another benefit arises from a factdiscovered by joint studies by the Institute

for Machine Tools and Business Studies at

the Technical University of Munich (iwb)

and the Association of German Machine

Tool Manufacturers (VDW). Until recently,

services to machines were in most cases

not part of design and planning, but were

individually adapted to the machine in

situ, with the associated effort and

expense.

Services such as the electrics, hydraulics

and pneumatics had to vie with one

another as to which of them wouldconnect to the machine first. Those that

followed had to compromise.

Consequently, a high proportion of

machine downtime was directly due to

faults in the services installation area. The

two organizations, together with

representatives of large customers,

representatives of manufacturers in the

various service disciplines and the German

Trade Associations worked out a concept

(known as DESINA 2) to change this

situation. It envisages the decentralization

of operating media, the standardization of

terminations for the three services

mentioned and standardization of the

oil-tight lines used [7].

Today, it is possible to actuate and receive

feedback from elements in the electrical,

hydraulic and pneumatic systems of

machines via a single bus system. There

are a large number of products built to

DESINA specifications on the market.

Termination designers have been given a

clear signal.

There are other reasons for

decentralization of the electrics being

desirable. One of them is the largeamounts machine manufacturers spend

on wiring for testing. The machine

operator can not make use of the

manufacturer‘s voluminous cable sets

afterwards. Another factor is the difficulty

at the commissioning stage, where several

people are necessary for communication

between the electrics on the machine unit

and the central control panel. In addition

to shortening the commissioning time,

decentralization also helps increase

personnel safety by spatially bringing

together the mechanical units with the

associated electrics. In this way, thesub-unit being worked on can be locally

isolated and secured against unwanted

restarting.

The benefits of modular networked

construction of the electrical equipment

are that it is:

• easier to design

• easier to engineer

• easier to produce and

• more efficient in application.

Taking the entire value creation chain intoaccount, networked electrical equipment

becomes systematically more economical

even though the price for individual

components may be initially higher

because of the built-in ”intelligence”3.

Installation, testing at the manufacturer’s

and commissioning at the operator’s

become more efficient. All the

components involved are visually, tangibly

and audibly close together which makes

fault tracing easier in the event of a

breakdown. It is also easier to match the

equipment to changed technical

requirements. The elimination of physicaleffects such as EMC problems and

travelling waves due to the reduction in

the cable lengths and the number of cores

involved, also speaks in favour of

decentralization of the electrical

equipment.

2 DESINA = Decentralized and StandardizedInstallation method for machine tools and

production systems

3 By “intelligence” here is meant only the buscapability and possibility of addressing thenetworked units, unlike with “decentralized“ or“distributed intelligence“ where sub-programs are

being processed locally in order to relieve the bus.

7

M1 M2 M3 M4 M5 M6 M7 M8

5

Fig. 6: The progressive complex multi-motor machine with highly dynamic interdependence

between some of its drives, and using a data and a power bus. The networkable switchgearand controlgear is housed in small, distributed cabinets, local to the motor.



Moeller offers progressive

networking solutions

• for the central control panel

(Fig.7)

• for decentralized configuration ofswitching and protective devices

(Fig.8) and

• for individual peripheral

switchgear units (Fig.9).

The busreplaces parallelwiring

Straightforward, fast communication

makes production processes moretransparent and more efficient. In

networks as described above, the

conventional multi-core parallel wiring is

replaced by wire-saving 2-core

connections or by fibre-optic cable. Each

element (switching device) in the network

is given an address, and as a slave takes

from the bus the information addressed to

it and feeds back to the bus its own

data/signals. For example, a contactor coil

receives from the bus the signal to switch

On the contactor, and a contactor contact

feeds back the information to the bus that

the contactor has closed. These pieces ofinformation are cyclically scanned and

transmitted. The interrelationships and

effects of these data/signals are processed

as application program by a bus master on

a PLC or an industrial PC. The program can

be centrally processed even with a

decentralized control system, or parts of

the program are processed locally by

so-called distributed intelligence. The rules

by which the information exchange and

the provision of power to the outputs for

actuation of the switching devices takes

place differ from bus system to bus system,

and there are many bus systems inexistence.

In some systems, power is taken from the

bus itself, in others it is fed in separately.

The power bus mentioned in the previous

paragraph generally refers to the mains

supply (primary current) to the motors or

other loads. Occasionally, it can also

provide power for sensors and actuators,

particularly for example in cases where,

because of the ratings involved, higher

voltages than are normally available from

the bus are required.

The evolution of networking has so far

taken place in three stages:

• In the first stage, some years ago,

devices were affected that are used

mainly as peripherals, in the field,

alongside the machine, in the

installation. In geographically

spread-out installations, the most

important motivating factors were to

save the enormous outlay on wiring

material and to simplify modifications.

• The second stage involved thenetworking within the control cabinet

of conventional switchgear and

protective devices. A few years ago,

these were of course still fitted

centrally together in one cabinet as

standard, and the panel builder

benefited greatly from the consequent

reduction in wiring within the

enclosure.

• The present, third stage is concerned

with the decentralization and

networking of switching and protective

devices. This evolutionary step does

away with the central control cabinet.

A major motivating reason, as

described, is the requirement for a

close alignment of mechanics and

associated electrics with one another.

Occasionally, this stage also entails the

autonomous decentralized processing

of certain automation tasks using small

controllers in order to reduce the load

on the bus. This ”distributed

intelligence” also enables test runs and

manual operation independently of theoverall control system.

In order for the idea of decentralization,

and above all, for networking to succeed,

it is vital also that safety-related functions,

such as Emergency-Stop should be

allowed to be carried out via an approved

”safety bus” that is accepted by the Trade

Associations. Otherwise, there would still

be a need for conventional wiring for

safety functions alongside the bus cables.

Recognized solutions have since emerged ,

but rapid standardization is required in

this area, in order to provide the user with

a safe and reliable choice.

Networking has the added advantages of

increasing personnel safety by the fact

that the bus systems are operated using

extra low voltages, and the reduction of

combustive energy within the electrical

equipment due to the absence of

multi-core control cables.

The latter benefit also brings significant

time and cost savings particularly in

spatially spread-out installations.

Subsequent expansion and modification

of the system as a rule are simplified and

become cost-efficient. Series connections,

previously normal, which could cause

faulty switching, are no longer necessary

in networked control systems [8]. Last, but

not least, the termination points, always

potential fault locations, are considerably

reduced in number.

8

Fig.7: Networked KLAS motor-startersfor fitting into panels(centralized solution).

These can be fitted to busbarsthat simultaneously distributethe mains supply, or to mountingrails. Networkable devices forfitting into switching cabinets

also include automation productsand networked frequencyinverters, for example.

Fig. 8: Networked KLAS motor-starterswith degree of protection IP 65,for distributed layouts, locally tomachines and in installations. Thestarters are supplied either withplugs, to conform to the DESINAstandard, or for direct connection.

Fig. 9: Networked switchgear for adistributed layout at the fieldlevel or locally to the machine.



the start. Flexibility of the infrastructure is

of course very much in demand in such

cases, in order to allow partitions set at a

later date or various different users to be

accommodated easily. But automation is

also conquering the single-unit family

home, and networking the individual

components is an important step towards

it. The benefits of networking were very

quickly recognized and applied by the

builders of turn-key residential units. The

remote indication of status or potential for

danger in a building and the remote

capability of reacting to the notification, is

a weighty argument in favour of

networking.

These aspects are comparable with the

motives for seeking a more qualified

diagnosis in industrial controls.

Extending theboundaries ofvoltage, frequencyand power

Generators too, in the widest sense, are

part of the Moeller philosophy entitled

”Moving more than motors“. For example,

Moeller is interested in equipping wind

generators with switchgear and protective

devices and with automation components.

There is a movement towards setting

whole ”forests“ of wind generators into

the oceans. The normal operational voltage

of such generators today is 690 V. To allow

the electrical energy produced by such

wind parks to be landed economically via

marine cable however, even higher

voltages are desirable, in order to reduce

the necessary cable sizes.

A similar picture also emerges from fields

of generators in the sea which use the

tides or ocean currents for the

manufacture of electricity. That is to say,any applications in which the cost of

cables represents a high proportion of the

investment, including mining operations

and technologies with high energy

density, are affected.

It is notable in this connection that various

Standards committees are striving to

extend the definition of Low Voltage

beyond 1000 V AC. The figures under

discussion are a lifting of the low-voltage

limit to 2000 Volt, with a new mains

voltage of 1200 V [11].

Once there is agreement on a new, higher

supply voltage, there will consequently be

a need also for drives and switchgear and

protective devices at this new level.

Considering semiconductors, the supply

voltage has a very strong bearing on price.

In such cases it will be necessary to weigh

up the savings against the higher costs of

operating equipment.

Moeller is already involved in the

development of circuit-breakers with a

short-circuit switching capacity of 150 kA,

for use with generators in shipboard

supply systems.

In a previous paragraph, mention was

made of high-speed drives in processing

machines. The frequencies for such drives

can reach into the kilohertz range, and will

make new demands on switchgear and

protective devices.

As long ago as the 1980ies, applications

arose in the machine building industry,which meant that several large

three-phase motors were running on one

common crown gear. Switchgear capable

of switching all the motors at the same

time was required. Such three-phase

low-voltage motors are easily expected to

have a rating of 750 kW!

The trendin switchgeardevelopment

At Moeller, electromechanical switching

devices are tending to be developed with

an ever greater proportion of

”intelligence“ built in [12].

In this way, they can then be directly

connected to the data bus and are capable

of two-way communication with the

control system via the bus. For reasons of

economy and better utilization of the bus

resources offered, the ”intelligence“ for

several switching devices is often jointly

located in their vicinity (group networking

[13]).

Just as there are open bus systems

nowadays, at Moeller we speak of open

switching devices that can have their

built-in ”intelligence“ matched for

connection to any of the known bus

systems. Two bus systems now dominate

within the switching cabinet and

alongside the machine, i.e. at the fieldbus

level. They are the actuator-sensor

interface (AS-i) and Profibus DP. From an

international point of view, there are one

or two more bus systems of note, such as

the Device Net.

This trend towards a union of switchgear

technologies and automation systems into

a cohesive system is further favoured by

the fact that automation systems are

tending away from established

programmable logic controllers and

towards the industrial PC and protocols

and operating systems used in IT and the

Internet. Above the fieldbus level

therefore, the Ethernet with TCP/IP

protocol is going to assert itself. The result

is web-based management.

At the Hannover Fair 2000, Moeller

showed prototypes of the new system,

Xtra Combinations (Fig.10), with

connection to Ethernet TCP / IP and MS

Windows®4, as example of a system in

which an industrial PC, the I/O level and

10

Fig.10: At the Hannover Fair 2000, Moeller introduced its first prototype of the XSystem. In thissystem, logic section, I/O modules and motor-starters as load outgoers are optimally tunedto one another.

4 Registered Trade Mark of the MicrosoftCorporation



load outgoers are combined in an elegant

way. The product groups of automation,

switchgear and power distribution are

thus converging into one system. There

are fewer interfaces, and synergies are

being utilized. Operating systems and

protocols that are widely known will

prevail, because they will reduce the

systems costs and the need for training.

Something once learnt, can easily be used

on a wider basis too.

Moeller is in the minority among

industrial switchgear producers in that the

electromechanical and electronic products

are jointly assigned to one Company unit,

and therefore under the same

management. This facilitates consistent

convergence of the two development and

production processes towards the

optimum for the user.

Alongside these hybrid products, work

goes on towards optimizing known

mechanical functions by using the latest

simulation methods, produced in-house,

or by the introduction of more up-to-date

technologies such as low-voltage vacuum

switching. The latest materials and

production methods also offer potential

for improvements.

Further studies at Moeller have revealed

that it would be sensible, and moreeconomical in the long run, to do away

with today’s individual devices, such as

contactors, overload relays, motor-

protective circuit-breakers, thermistor

protective devices and circuit-breakers, in

favour of combining their required

functions into completely new types of

system.

One important step on this path is already

being taken in that in Germany too, there

is more talk of motor-starters than ofcontactors and motor-protective devices.

At present, individual functions are often

duplicated, e.g. the switching function is

carried out by both contactor and circuit-

breaker. In protective functions on the

other hand, it is necessary to compromise

in order to protect both the motor and the

cable.

These brand-new systems that are in their

early development at Moeller at the

moment, will, of course, also change the

present-day methods of mounting and

wiring in the switching cabinet. This willmean that the so far largely independent

product groups switching, protection and

automation devices and systems on the

one hand, and enclosures, mounting and

wiring systems on the other, will grow

together. The independent panel builder

nowadays, may obtain these groups of

products from different manufacturers.

The optimum value for money will

however be offered by one closed system

incorporating all the functions.

The time for such developments has not

yet come. There are four significant factorsat present preventing their

implementation and introduction:

1. As the market stands today, both

simple and complex switching and

[1] Wolfgang Esser, [[Study: All about themotor]], Moeller GmbH, 1995, unpublished

[2] Wolfgang Esser, [[Study: All about themachine]], Moeller GmbH, 1995,unpublished

[3] Moeller Motor Working Party, [[Automationstrategy around the processing machine]],Moeller GmbH, 1995, unpublished

[4] Wolfgang Esser, [[Soft starting of motorsusing electronic motor-starters]], MoellerGmbH, VER 89-781

[5] Wolfgang Esser, [[Switchgear suitable for

tying motors and electrical equipment intothe working processes of the future; Part 1:Trends regarding machines and electricalequipment]], in German, in ‘der Elektro-meister + deutsches Elektrohandwerk,Volume 8/1997

[6] Wolfgang Esser, [[Switchgear for theprotection of electric motors]], MoellerSpecialist Publication, FB 0200-0021 D,2nd Edition, 1999

[7] G. Reinhart / J. Milberg, seminar reports1995 9: [[Installation technology onmachine tools, analyses and concepts]],published by Herbert Utz Scientific Books,1995; for further information see also:www.desina.de

[8] Wolfgang Esser, [[Aspects of functionallysafe engineering of contacting controlcircuits]], Moeller GmbH, VER 08+43+787,1993

[10] Wolfgang Esser, [[Comfort and safety viathe EIB “ F&G Home Manager]], MoellerGmbH, 2000

[11] Gerhard Voß, Mannheim, [[A convincingmajority in favour of lifting the low-voltagelevel up to 2000 V]], in ‘Elektrizitätswirt-schaft’, year 99 (2000), Volume 6

[12] Wolfgang Esser, [[Switchgear suitable fortying motors and electrical equipment intothe working processes of the future; Part 2:Switchgear and protective devices for thefuture]], in German, in ‘der Elektromeister +deutsches Elektrohandwerk, Volume 9/1997

[13] Wolfgang Esser, [[Open for everything –networking switching devices with variousprotocols]], Moeller GmbH, Specialpublication from ”Practical Electronics“No. 19/1997, VER 97-873, 1997

11

protective functions have to be covered

by the same products.

2. Simple tasks (volume applications) are

served well by present-day products.

3. Industrial customers especially, want tobe able to obtain similar products from

several suppliers as a second source.

This notion makes the introduction of

new and innovative systems difficult,

because of the lack of a ”second

source”.

4. The Standards of today indirectly

presuppose the present situation as far

as products are concerned. There are

clear differences between the

Standards for example in Europe and in

America. This also applies to traditions

of use and to dimensioning.

Innovative productsfor efficient drives,for today andtomorrow

Some of the first products based on the

new Moeller philosophy are already in

existence.

The new and innovative products for theautomation of drives (Fig.10) will be

described in special Moeller articles with all

their features and benefits, as and when

they are being launched into the market.

Bibliography:



E-Mail: [email protected]: www.moeller.net

© 2001 by Moeller GmbH

Subject to alterations

VER 2100+2300-920 GB-INT DM 04/01

Printed in the Federal Republic of Germany (05/01)

Xtra Combinations is the new worldof automation from Moeller. This meansthat one company can now serve allyour automation requirements. Moelleris your competent partner for buildingautomation, industrial automationand power distribution. We provide

a complete package, or individualcombinations depending on yourapplication. And everything fits togetherperfectly: core products, PLCs, data andprocess display units, communicationproducts, SIMATIC® software standards,accessibility via the Internet, design andsolution competence, and professionalservices. All backed up by Moeller’sexperience and expertise, spanningmore than 100 years, with switchgear,controlgear and PLC technology inthe fields of automation and powerdistribution. What other company offersyou so much from a single source?Contact us, we’d like to talk to you.

SIMATIC® is a Siemens AG brand name

Think future. Switch to green.

tra Combinations

moving more than motors

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