Motor starters

Star-delta starter

 

This is the most popular and commonly

used starting method for motor ratings

> 4 kW (400 V).

 

• Electronic motor starter (EMS) and soft

starter

These enable the soft and low-noise

starting of the motor. This eliminates

interference producing current peaks

and jerks during switching. The startup

and deceleration phase of the motor can

also be time-controlled depending on the

load.

 

• Frequency inverter

This enables time-controlled motor

starting, motor braking and operation

with infinitely variable motor speeds.

Depending on the application, different

types of frequency inverters are used:

– with the voltage/frequency control

(U/f) or vector control for

frequency-controlled motor operation,

– with vector control or servo control for

high speed accuracy and additional

torque adjustment.

Associated circuit diagrams

Direct on line starter

Direct-on-line starter

 

In the simplest case the motor is

connected directly with a contactor. The

combination of motor protection and

cable protection (fuse) is called a motor

starter (MSC = Motor Starter

Combination).

By applying the full mains voltage to the

motor windings, DOL starting may

produce large starting currents which

may result in troublesome voltage

changes. Direct-on-line starting

three-phase motors must not cause

interference voltage changes in the

public utility grid. This requirement is

generally fulfilled if the apparent power

of a three-phase asynchronous motor

does not exceed 5.2 kVA or its startup

current does not exceed 60 A.

With a mains voltage of 400 V and 8 times

the starting current, this corresponds to

a rated motor current of around 7.5 A and

thus a motor rating of 4 kW.

The motor rating denotes the mechanical

output of the motor at the shaft.

CB Number of poles

Standards

CE

The CE conformity marking shall indicate conformity to all the obligations imposed

on the manufacturer, as regards his products, by virtue of the European

Community directives providing for the affixing of the CE marking.

 

When the CE marking is affixed on a product, it represents a declaration of the

manufacturer or of his authorized representative that the product in question

conforms to all the applicable provisions including the conformity assessment

procedures. This prevents the Member States from limiting the marketing and

putting into service of products bearing the CE marking, unless this measure

is justified by the proved non-conformity of the product.

Flow diagram for the conformity assessment procedures established by the Directive

2006/95/CE on electrical equipment designed for use within particular voltage range:

Manufacturer

Technical file

The manufacturer

draw up the technical

documentation

covering the design,

manufacture and

operation of the

product

EC declaration of

conformity

The manufacturer

guarantees and declares

that his products are in

conformity to the technical

documentation and to the

directive requirements

 

Naval type approval

The environmental conditions which characterize the use of circuit breakers for

on-board installations can be different from the service conditions in standard

industrial environments; as a matter of fact, marine applications can require

installation under particular conditions, such as:

- environments characterized by high temperature and humidity, including saltmist

atmosphere (damp-heat, salt-mist environment);

- on board environments (engine room) where the apparatus operate in the

presence of vibrations characterized by considerable amplitude and duration.

In order to ensure the proper function in such environments, the shipping registers

require that the apparatus has to be tested according to specific type

approval tests, the most significant of which are vibration, dynamic inclination,

humidity and dry-heat tests.

 

 

Standards

“Low Voltage” Directive 2006/95/CE

The Low Voltage Directive refers to any electrical equipment designed for use

at a rated voltage from 50 to 1000 V for alternating current and from 75 to

1500 V for direct current.

In particular, it is applicable to any apparatus used for production, conversion,

transmission, distribution and use of electrical power, such as machines,

transformers, devices, measuring instruments, protection devices and wiring

materials.

The following categories are outside the scope of this Directive:

• electrical equipment for use in an explosive atmosphere;

• electrical equipment for radiology and medical purposes;

• electrical parts for goods and passenger lifts;

• electrical energy meters;

• plugs and socket outlets for domestic use;

• electric fence controllers;

• radio-electrical interference;

• specialized electrical equipment, for use on ships, aircraft or railways, which

complies with the safety provisions drawn up by international bodies in which

the Member States participate.

 

Directive EMC 2004/108/CE (“Electromagnetic Compatibility”)

The Directive on electromagnetic compatibility regards all the electrical and electronic

apparatus as well as systems and installations containing electrical and/

or electronic components. In particular, the apparatus covered by this Directive

are divided into the following categories according to their characteristics:

• domestic radio and TV receivers;

• industrial manufacturing equipment;

• mobile radio equipment;

• mobile radio and commercial radio telephone equipment;

• medical and scientific apparatus;

• information technology equipment (ITE);

• domestic appliances and household electronic equipment;

• aeronautical and marine radio apparatus;

• educational electronic equipment;

• telecommunications networks and apparatus;

• radio and television broadcast transmitters;

• lights and fluorescent lamps.

The apparatus shall be so constructed that:

a) the electromagnetic disturbance it generates does not exceed a level allowing

radio and telecommunications equipment and other apparatus to operate

as intended;

b) the apparatus has an adequate level of intrinsic immunity to electromagnetic

disturbance to enable it to operate as intended.

An apparatus is declared in conformity to the provisions at points a) and b) when

the apparatus complies with the harmonized standards relevant to its product

family or, in case there aren’t any, with the general standards.

ABB MCC

Control Circuits

Control Circuits

Control  Control components are used in a wide variety of applications with varying degrees of complexity. One example of a simple control circuit is a circuit that turns a light on and off. In this circuit, the control component is often a single-pole switch.

 

 

Control circuits used in commercial and industrial applications tend to be more complex than this simple circuit and employ a broader variety of components. However, the function of these circuits is often the same, to turn something on and off. In some cases, manual control is used. More often, automatic control circuits or circuits that combine manual and automatic control are used.

 

 

Electrical Panel

Pollution Degree

The level of pollution in the environment in which the Assembly is intended to be

installed. Four categories are defined in the Standard as follows:

 

Pollution degree 1 : No pollution or only dry, non-conductive pollution occurs.

Pollution degree 2 : Normally, only non-conductive pollution occurs. Occasionally, however, a temporary

                             conductivity caused by condensation may be expected.

Pollution degree 3 : Conductive pollution occurs, or dry, non-conductive pollution occurs which becomes

                             conductive due to condensation.

Pollution degree 4 : The pollution generates persistent conductivity caused, for instance, by conductive dust or by

                             rain or snow.

 

Unless advised otherwise, the Standard and the manufacturer will assume

pollution degree 3 is applicable for industrial applications.

ROUTINE TESTS

These tests have a totally different function to Type Tests, BS EN 60439-1, states:

 

‘Routine tests are intended to detect faults in materials and workmanship. They are carried

out on every ASSEMBLY after its assembly or on each transport unit. Another routine test

at the place of installation is not required.’

 

Hence, Routine Tests on Assemblies are normally undertaken at the

manufacturer’s premises, and are:

• part of the quality control activity. They are intended to ensure materials and

workmanship included in every assembly produced meet the standards required

by the design.

• carried out on every assembly or transportable unit to be put into service. It is

recognized that it is unnecessary, with modern modular designs, to fully couple

assemblies for routine test, if they are subsequently to be shipped in several

sections.

• of a non-destructive nature having minimal effect on the service life of the

equipment.

• not intended to duplicate routine tests, previously carried out on components as

part of their manufacturing process.

• not intended to be repeated on site. This does not remove the onus of the

installer to ensure the assembly’s correct installation and obligation to test under

BS 7671. Before tests under BS 7671, or other testing is undertaken, the effects

of these tests on voltage sensitive components should be established.

 

(BEAMA Installation)

PARTIALLY TYPE TESTED ASSEMBLY (PTTA)

IEC 60439-1, defines a PTTA as:

‘A low-voltage switchgear and controlgear assembly, containing both type-tested and nontype-

tested arrangements provided the latter are derived (e.g. by calculation) from type tested

arrangements which have complied with the relevant tests’.

 

This means:

• The assembly will be derived from a Type Tested Assembly.

• Deviations from the tested configuration are only permitted provided they can

be verified by calculation or equivalent methods. Such methods have their

limitations which must be fully understood and, where appropriate, allowed for

through safety factors in the analysis.

• As a means of demonstrating design compliance with the Standard,

manufacturers must have available Type Test documentation for the original

design and any calculations relating to modified elements.

• The Assembly will consist, as far as practical, of a series of standard elements

configured to suit a particular application. Customisation should be restricted to

situations where it cannot be avoided, e.g. facilities for terminating over size

cables, use of an alternative tested component, etc.

• All components and devices will be fully Type Tested to their respective product

standards. Documentation will be available for examination.

• Combinations of Type Tested components and devices installed in an otherwise

untested Assembly are not covered by this definition and the Standard.

 

(BEAMA Installation)

TYPE TESTED ASSEMBLY (TTA)

IEC 60439-1, defines a TTA as:

 

‘A low-voltage switchgear and controlgear assembly conforming to an established type or

system without deviations likely to significantly influence the performance, from the typical

ASSEMBLY verified to be in accordance with this standard.’

 

This means:

• The generic design of the Assembly including all the various elements used in its

construction have completed the Type Tests detailed in the Standard.

• Deviations from the tested configuration are permitted, but they will be very

minor and not ‘likely to significantly influence the performance’ e.g. a functional unit

may have been short circuit tested in the top of the Assembly and in service be

located lower down.

• Design verification must be via stringent testing, and does not rely on subjective

assessments, calculations, safety margins and engineering judgements.

• The Assembly will consist of a series of standardized elements including

interconnections, all of which have previously been proven by tests in the Type

Tested Assembly(s), but may be configured differently to suit the application.

• Assemblies may be built by licensed assemblers under strict controls.

 

(BEAMA Installation)

Current ratings

Rated current (In)

 

value of current, declared by the ASSEMBLY manufacturer taking into consideration the ratings

of the components, their disposition and application, which can be carried without the

temperature-rise of various parts of the ASSEMBLY exceeding specified limits under specified

conditions

 

Rated peak withstand current (Ipk)

value of peak short-circuit current, declared by the ASSEMBLY manufacturer, that can be

withstood under specified conditions

 

Rated short-time withstand current (Icw)

r.m.s value of short-time current, declared by the ASSEMBLY manufacturer, that can be carried

without damage under specified conditions, defined in terms of a current and time

 

Rated conditional short-circuit current (Icc)

value of prospective short-circuit current, declared by the ASSEMBLY manufacturer, that can be

withstood for the total operating time (clearing time) of the short-circuit protective device

(SCPD) under specified conditions