Type 2 Switchgear Combination

8/23/2019 Type 2 Switchgear Combination

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Article on Type 2 as per IS


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What is CoWhat is Co--ordination?ordination?

An optimized combination of

Switching Device

Overload Protecting Device (OLPD)

Short Circuit Protecting Device (SCPD)

.... To ensure protection of personnel and equipment in the event

of fault


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Problem with non coProblem with non co--ordinated feedersordinated feeders

Erratic tripping of Protective Devices

Burning of motors

Altered tripping characteristics of overload relays

requen p ng we ng o con ac s

Damaged Insulation of components

Danger to life of operating personnel=


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Motor should not stop when..- running on rated load- drawing starting current for permissible starting time

- utilized to permissible short time overload capacity- put in service according to utilization category

Objective of CoObjective of Co--ordinationordination

- between overload and short circuit protecting device

Protection

- of switching and overload device during short circuit


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Two types of co-ordination are permissible, "1" or "2".

Type "1" co-ordination requires that, under short-circuit conditions, the contactor or startershall cause no danger to persons or installation and may not be suitable for further

service without repair and replacement of parts.

T e "2" co-ordination re uires that under short-circuit conditions the contactor or

Co-ordination as per IEC 60947-4-1

starter shall cause no danger to persons or installation and shall be suitable for furtheruse. The risk of contact welding is recognized, in which case the manufacturer shallindicate the measures to be taken as regards the maintenance of the equipment.

Use of an SCPD not in compliance with the manufacturer's recommendations mayinvalidate the coordination.


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How it is achieved?How it is achieved?

The selection of devices is done in such a way so that

The time-current characteristics of OLPD and SCPD must allows sufficienttime for the motor to run up

SCPD must protect the OLPD from destruction by overload currentsexceeding approximately 10 times its rated current

mus n errup curren s w c are oo arge o e sw c e o ycontactor (short circuit currents)

SCPD must protect the contactor in the event of short circuit

SCPD Short Circuit Protecting DeviceOLPD Over Load Protecting Device


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t

OLPD Curve

SCPD Curve

Annexure 4:Trippingcharacteristics of

various products

Ian

OLPD and SCPD must allows sufficient time for the motor to run up


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tst

OLPD destructionCurve

Ian

SCPD must protect the OLPD from destruction


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SCPD must protect the contactor in the event of short circuit

Contactor curve forseparable welding


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The short circuit test is done at two operational conditions

a) with all the switching devices closed prior to the test

b) closing the contactor or starter on to the short-circuit current


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MPCB

Overload curveShort circuit curve

MPCB MCB

MCB

Overload curveShort circuit curve

Comparison the curve of MCB / contactor andType 2 co-ordinated MPCB / contactor combination

MPCBOverload destruction curve

ContactorContactor curve for

separable welding


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Blower Motor ` MPCB

KW: 1.1 kW MCB

Amps: 2.6 A Contactor welding curve

2000

1000

500

200

100

50

20

10

5

Present

MCB 6AContactor 16A

Type 2MPCB : 2.2 3.2AContactor 12A

2

0.1

0.05

0.05

0.01

0.005

0.002

1.6 2.1 3 5 8 16 21 26 52 78 104 156 Amps


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Present situationAC coaches

ContactorMPCB

Short Circuit

Type 2 co-ordinatedswitchgear

MCB

Birelay Contactor

Type 2 co-ordination

Contactor

Documents

Type 2 Switchgear Combination