Standards
• IS 13947
• IEC 60947
• Below or Equal to
1000V for AC
&
1200V for DC
SWITCHGEAR SWITCHING PROTECTION
CONTACTOR
RELAY
STARTER
SWITCH / SD
HRC FUSE
SFU/FSU/SDF
ACB
MCCB
MPCB
Y
N
Y
N
Y
N
Y
Y
N
Y
Y
Y
Y
Y
Y
Y
Y
Y
CONTACTOR As per IS 13947
PART 4
A mechanical switching device having
only one position of rest operated
otherwise than by hand, capable of
making, carrying and breaking
currents under normal circuit
condition including operating
overload condition.
CONTACTOR
A SIMPLE ELECTROMAGNETIC SWITCH
FOR
FREQUENT OPERATION
WITH
NO - VOLT PROTECTION
Core competency
High Operational Life
CONTACTOR MAIN APPLICATION AREAS





SWITCHING OF MOTORS
SWITCHING OF LIGHTING LOADS
SWITCHING OF HEATING LOADS
SWITCHING OF CAPACITORS
SWITCHING OF DC LOADS
SYMBOLS FOR CONTACTOR
MAIN CIRCUIT
2/T1
4/T2
6/T3
1/L1
3/L2
5/L3
SYMBOLS FOR CONTACTOR
AUXILIARY CIRCUIT
A1
A2
13
14
21
22
LIMITS OF OPERATION
Pick Up – 85% to 110% of Uc
Drop Off – 75% to 20% of Uc ( for a.c.)
75% to 10% of Uc (for d.c.)
Where Range is specified
75% & 85% shall apply to Lower Value
110%, 20% & 10% shall apply to Higher Value
WHY CONTACTOR ?
 HIGH OPERATIONAL LIFE
 HIGH FREQUENCY OF OPERATION
 CAN BE OPERATED FROM REMOTE
 CAN BE USED FOR AUTOMATIC
SWITCHING OPERATIONS
 CAN OFFER NO VOLT
PROTECTION
SELECTION OF
CONTACTOR
PARAMETERS
 RATED OPERATIONAL VOLTAGE, Ue
 RATED OPERATIONAL CURRENT, Ie
 FREE AIR OR ENCLOSED THERMAL
CURRENT, Ith & Ithe
 UTILIZATION CATEGORY
 ELECTRICAL & MECHANICAL LIFE
SELECTION OF CONTACTOR
PARAMETERS








RATED CONDITIONAL S/C CURRENT
FREQUENCY OF OPERATION
COIL VOLTAGES
NUMBER OF AUXILIARY CONTACTS
DIMENSIONS
TERMINAL SIZE
EASE OF MAINTENENCE
AVAILABILITY OF SPARES
SELECTION OF CONTACTOR
UTILISATION CATEGORIES
AC 1
NON-INDUCTIVE / SLIGHTLY INDUCTIVE
LOADS,RESISTANCE FURNACES
AC 2
SLIP RING MOTORS: STARTING ,
SWITCHING OFF
AC 3
SQUIRREL CAGE MOTORS : STARTING,
SWITCHING OFF DURING RUNNING
AC 4
SQUIRREL CAGE MOTORS : STARTING,
PLUGGING & INCHING
SELECTION PARAMETERS
UTILISATION CATEGORIES
AC 5a
SWITCHING OF ELECTRIC DISCHARGE
LAMP CONTROLS
AC 5b
SWITCHING OF INCANDESCENT LAMPS
AC 6a
SWITCHING OF TRANSFORMERS
AC 6b
SWITCHING OF CAPACITOR BANKS
VERIFICATION OF NUMBER OF ON LOAD
OPERATINAL PERFORMANCE
( MAKING & BREAKING CONDITIONS
ACCORDING TO UTILISATION CATEGORY )
Make
Break
Utilization
Cat.
I / Ie
U / Ue
COSj
Ic / Ie
Ur / Ue
COSj
AC 1
1
1
0.95
1
1
0.95
AC 2
2.5
1
0.65
2.5
1
0.65
AC 3
6
1
0.35
1
0.17
0.35
AC 4
6
1
O.35
6
1
O.35
SELECTION PARAMETERS
ELECTRICAL DURABILITY
NO. OF OPERATING CYCLES
A TYPICAL ELECTRICAL LIFE CURVE FOR UTILISATION CATEGORY AC4
OPERATING CURRENT IN AMPERES
SELECTION PARAMETERS
ELECTRICAL LIFE IN MIXED
DUTY APPLICATION
A
N =
1 +
C
100
A
B
1
WHERE, N = ELECTRICAL LIFE IN MIXED DUTY
A = ELECTRICAL LIFE IN AC 3 DUTY
B = ELECTRICAL LIFE IN AC4 DUTY
C = PERCENTAGE OF AC 4 OPERATION OF TOTAL
OPERATION
RELAY
• A device designed to produce
sudden predetermined changes in one
or more electrical output circuit
when certain condition are fulfilled
in electrical input circuit controlling
the device.
BIMETAL OVERLOAD RELAY
ADVANTAGES :
1.
2.
3.
4.
5.
6.
7.
THERMAL MEMORY
ACCURATE PROTECTION
ADJUSTIBILITY
AMBIENT COMPENSATION
COMPACT CONSTRUCTION
LONG LIFE
ECONOMICAL
BIMETALLIC OVERLOAD RELAY
WITH DOUBLE SLIDE MECHANISM
BIMETAL
UPPER SLIDE
LEVER
STOPPER
LOWER SLIDE
As per IS : 13947 Part 4
Trip Classes for All Relay
Multiple of
Set Current
(Tripping Time)
1.05
≥ 2 hours
1.2
≤ 2 hours
10A
10
20
30
1.5
< 2min.
< 4min
< 8min
< 12min
7.2
2-10sec
4-10sec
6-20sec
9-30sec
SELECTION OF BIMETAL OVERLOAD RELAYS
1.
FIND OUT THE NAME PLATE CURRENT OF MOTOR
OR
CALCULATE THE FULL LOAD CURRENT
KW * 1000
I FULL LOAD
=
 3 * LINE VOLTAGE * COS j
2 . SELECT SUITABLE RELAY RANGE
( ENSURE THAT FULL LOAD CURRENT OF THE
MOTOR IS TOWARDS THE MAX. RANGE OF RELAY)
3.
ENSURE THAT RELAY TRIP CURVE IS BELOW THE
MOTOR WITH STAND CURVE ( IF AVAILABLE )
SETTING OF BIMETAL OVERLOAD RELAYS
1.
FIND OUT THE NAME PLATE CURRENT OF MOTOR
2.
MEASURE THE ACTUAL CURRENT DRAWN BY THE
MOTOR.
3.
SET THE RELAY AS PER THE ACTUAL CURRENT
DRAWN BY THE MOTOR.
( IF THE ACTUAL CURRENT DRAWN IS MORE THAN
THE NAME PLATE CURRENT, INVESTIGATE THE
CAUSE FOR OVERLOADING )
4.
IN CASE OF STAR - DELTA STARTER, CHECK UP
WHETHER RELAY IS IN LINE OR PHASE CIRCUIT.
SELECTION AND SETTING OF BIMETAL OVERLOAD RELAYS
( FOR MOTORS WITH LONG STARTING TIME )
IF THE STARTING TIME OF THE MOTOR IS MORE THAN THE
RELAY TRIP TIME AT STEADY STATE STARTING CURRENT,
1. SELECT A RELAY WITH DELAYED TRIPPING CHARACTERISTICS &
ENSURE THAT RELAY TRIP TIME AT STEADY STATE STARTING
CURRENT IS MORE THAN THE STARTING TIME OF THE MOTOR.
2. SET THE RELAY AS PER THE ACTUAL CURRENT DRAWN BY
THE MOTOR
NOTE : IN CASE OF MOTOR STARTING TIME BEING MORE THAN THE
TRIPPING TIME OF THE RELAY EVEN FOR RELAY WITH DELAYED
TRIPPING CHARECTERISTICS AT STARTING CURRENT , BY PASS
THE RELAY DURING STARTING.
WHAT IS A MOTOR
STARTER ?
IT IS A COMBINATION UNIT OF
CONTACTOR (S) AND A RELAY
USED FOR SWITCHING AND
OVERLOAD PROTECTION OF
THE MOTOR.
FULLY AUTOMATIC STAR DELTA STARTER
HRC FUSE
MAIN APPLICATION AREAS
 AS A S.C.P.D. IN MOTOR STARTER FEEDERS
 PROTECTION OF LIGHTING & HEATING
CIRCUITS
 PROTECTION OF TRANSFORMERS
 PROTECTION OF CABLES
 BACK-UP TO CBs WHERE FAULT LEVEL
EXCEEDS BREAKING CAPACITY OF THE CB
 PROTECTION OF SMALL LOADS ON CIRCUITS
HAVING HIGH FAULT LEVELS
CUT SECTION OF HRC FUSE
CONTACT
POP UP INDICATOR
HIGH RESISTANCE WIRE
BODY
QUARTZ SAND
FUSE ELEMENT
WHY HRC FUSE ?
• EXTREMELY HIGH BREAKING CAPACITY OF UP
TO 100KA
• VERY FAST OPERATION IN THE EVENT OF
HEAVY S/C (CAN INTERRUPT EVEN IN < 5
mSEC)
• CURRENT LIMITING DEVICE
- LIMITS S/C CURRENT TO A VALUE
LESS THAN PROSPECTIVE PEAK
- VERY LOW LET THRU’ ENERGY
• NO MAINTENANCE REQUIRED
• VERY SMALL/COMPACT SIZE
• RELATIVELY LOW COST
SELECTION PARAMETERS
RATED POWER DISSIPATION
AS PER IS 13703/PART 2 FOR gG FUSE LINK
SIZE
In
(A)
MAXIMUM PERMISSIBLE
POWER DISSIPATION (W)
00
0
1
2
3
4
100/160
160
250
400
630
1000
7.5/12
16
23
34
48
90
SELECTION PARAMETERS
CO-ORDINATION WITH STARTER
TYPE 1 CO - ORDINATION
REQUIRES THAT, UNDER SHORT-CIRCUIT CONDITIONS, THE
CONTACTOR OR STARTER SHALL CAUSE NO DANGER TO PERSONS OR
INSTALATION AND MAY NOT BE SUITABLE FOR FURTHER SERVICE
WITHOUT REPAIR AND REPLACEMENT OF PARTS
TYPE 2 CO - ORDINATION
REQUIRES THAT, UNDER SHORT SHORT-CIRCUIT CONDITIONS, THE
CONTACTOR OR STARTER SHALL CAUSE NO DANGER TO PERSONS OR
INSTALLATIION AND SHALL BE SUITABLE FOR FURTHER USE. THE RISK OF
CONTACT
WELDING IS RECOGNIZED, IN WHICH CASE THE
MANUFACTURER SHALL INDICATE THE MEASURES TO BE TAKEN AS
REGARDS THE MAINTENANCE OF THE EQUIPMENT
SELECTION OF HRC FUSE
TYPE 2 COORDINATION
TIME (SEC)
RELAY
CH.
FUSE
CH.
CONTACTOR
BR. CAPACITY
CROSS-OVER
POINT
MOTOR
CURRENT

1
2 3 4 5 6 7
CURRENT (n  IrM)
8
9
10
SELECTION OF HRC FUSE
PARAMETERS
 RATED VOLTAGE








RATED CURRENT
RATED BREAKING CAPACITY
TYPE
SIZE
TIME-CURRENT CHARACTERISTICS
COORDINATION WITH STARTER
RATED POWER DISSIPATION
DISCRIMINATION WITH OTHER SCPDs
SWITCHES, DISCONNECTORS,
SWITCH DISCONNECTOR &
FUSE COMBINATION UNIT
AS PER IS 13947 (PART 3)
SWITCH
A MECHANICAL SWITCHING DEVICE
CAPABLE OF MAKING , CARRYING AND
BREAKING CURRENTS UNDER NORMAL
CONDITIONS WHICH MAY INCLUDE SPECIFIED
OPERATING OVERLOAD CONDITIONS.
SHALL BE ABLE TO CARRY FOR A
SPECIFIED TIME CURRENTS UNDER SPECIFIED
ABNORMAL CONDITIONS SUCH AS THOSE OF
SHORT CIRCUIT.
WHY S/W-DISCONNECTOR ?
 FOR ISOLATING THE MOTOR FEEDER FOR
ANY MAINTENANCE WORK
 CAN BE USED AS BACK-UP SWITCHING
DEVICE IN CASE OF EMERGENCIES (LIKE
CONTACTOR WELDING)
 POSITIVE OPENING OF MAIN CONTACTS
 ADDITIONAL FACILITIES LIKE DOOR
INTERLOCK & PADLOCKING
EQUIPMENT DEFINITION
FUNCTION
MAKE - CARRY - BRAEAK
CURRENT
ISOLATION & CARRY
SWITCH
DISCONNECTOR
SWITCH FUSE
DISCONNECTOR FUSE
FUSE - SWITCH
FUSE - DISCONNECTOR
MAKE-CARRY- BREAK
& ISOLATION
SWITCH DISCONNECTOR
SWITCH
DISCONNECTOR - FUSE
FUSE - SWITCH DISCONNECTOR
UTILIZATION CATEGORY
FREQUENT
INFREQUENT
TYPICAL
OPERATION
OPERATION
APPLICATION
AC20 A
AC 20 B
CONNECTING & DIS- CONNECTING
UNDER NOLOAD CONDITIONS
AC 21 A
AC 21 B
SWITCHING OF RESITIVE LOADS
INCLUDING MODERATE OVERLOADS
AC 22 A
AC 22 B
SWITCHING OF MIXED RESISTIVE
& INDUCTIVE LOADS , INCLUDING
MODERATE OVERLOADS
AC 23 A
AC 23 B
SWITCHING OF MOTOR OR HIGHLY
INDUCTIVE LOADS
Motor Protection Circuit
Breakers
(MPCBs)
ADVANTAGES :
• FUSELESS PROTECTION SYSTEMS WITH LOW
DOWN TIME
• INTEGRATED COMPREHENSIVE PROTECTION
• LOWER LET THROUGH ENERGY
• COMPACT
• AVAILABILITY OF VARIOUS ACCESSORIES
• HIGH ELECTRICAL LIFE
• HIGH BREAKING CAPACITY
• EASE OF CO-ORDINATION
Accessories with MPCB
• AUX. CONTACTS
* INDICATE ---- ON / OFF POSITION
---- TRIP same as OFF
• TRIP INDICATING AUX. CONTACTS
*S/C signaling contacts
*O/L signaling contacts
• SHUNT RELEASE ----- REMOTE TRIPPING
• UNDER VOLTAGE RELEASE
• DOOR COUPLING HANDLE
Type 2 co-ordination
Application : Stand alone device
determination of cross over point
T
I
M
E
CROSS OVER
POINT ( IN BUILT )
MOTOR
CURRENT
MPCB
5-6In
CURRENT
14In
MPCB SCHEME 1
SCHEME IS RECOMMENDED WHEN
SWITCHING OF MOTOR IS INFREQUENT
MPCB
MPCB PROVIDES :
I>
* PROTECTION AGAINST SHORT CIRCUIT
* PROTECTION AGAINST OVER LOAD + S/P
M
MOTOR
* SWITCHING OF MOTOR
MPCB SCHEME 2
SCHEME IS RECOMMENDED WHEN
SWITCHING OF MOTOR IS FREQUENT
MPCB
MPCB PROVIDES :
I>
* PROTECTION AGAINST SHORT CIRCUIT
* PROTECTION AGAINST OVER LOAD + S/P
CONTACTOR
CONTACTOR IS USED FOR
MOTOR
M
*SWITCHING OF MOTOR UNDER NORMAL
CONDITION
MPCB SCHEME 3
MPCB PROVIDES :
* PROTECTION AGAINST SHORT CIRCUIT
MPCB
I>
O/L RELAY PROVIDES :
* PROTECTION AGAINST OVER LOAD + S/P
O/L RELAY
CONTACTOR IS USED FOR
CONTACTOR
MOTOR
* SWITCHING OF MOTOR UNDER NORMAL
CONDITION
* SWITCH OFF MOTOR ON TRIP COMMAND
M
FROM RELAY OUTPUT