Page 946 - Motor protection and control Manual motor starters, contactors and overload relays

13/8 ABB MOTOR PROTECTION AND CONTROL

—

Coordination with short-circuit protection devices

Definition Types of coordination
The coordination of control and protection devices In IEC 60947-4-1 (EN 60947-4-1) UL 60947-4-1 between the branch
compliance with IEC 60947-4-1, EN 60947-4-1 and UL 60947-4-1 circuit protective device and the motor starter defines two
between the branch circuit protective device and the motor types of coordination according to the expected level of service
starter standards defines for the contactors and starters the continuity. Acceptable extreme damage for the switchgear is
type rating and characteristics of the short-circuit protection divided into two types.
devices SCPD which allow selective protection against • Type 1: In short-circuit conditions, the contactor or starter
overloads and ensure protection against short circuits. does not endanger persons or installations and will not be
Basic functions able to then operate without being repaired or having parts
Any starter is designed to: replaced.
• start motors, • Type 2: In short-circuit conditions, the contactor or starter
• ensure continuous functioning of motors, does not endanger persons or installations and will be able to
• disconnect motors from the supply line, operate afterwards. The risk of contacts light welding is ac-
ceptable. In this case, the manufacturer must stipulate the
• guarantee protection of motors against overloads. measures to be taken with respect to maintenance of the
The starter is typically made up of a switching device equipment.
(contactor) and an overload protection device (thermal overload
relay or electronic overload relay). These two devices MUST be Motor efficiency class and design type
coordinated with equipment capable of providing protection IEC coordination tables are displayed for IE1, IE2 and IE3 motor
against short circuit (SCPD: short circuit protective device): efficiency classes in regards with N/H or NE/HE motor design
typically a circuit breaker with magnetic release only or a switch use.
fuse. These are not necessarily part of the starter.
Asynchronous IE1/IE2/IE3/IE4 motors may be of the design N
Applicable standards or H.
IEC 60947-4-1 (EN 60947-4-1) and UL 60947-4-1 between the Asynchronous IE3/IE4 motors may be of the design NE or HE,
branch circuit protective device and the motor starter precisely having extended / locked rotor apparent power and current
defines the different points to be considered in order to carry than design N and H motors.
out correct coordination. Complete coordination for a combina- • International Efficiency (IE) classes for single speed
tion includes the following points: electric motors
• selectivity test between the overload relay and the short pro- IEC 60034-30-1:2014 standard defines four International Effi-
tection device SCPD. ciency (IE) classes for single speed three-phase cage rotor in-
• short-circuit condition tests: duction motors designed for operation on sinusoidal voltage:
at prospective "r" currents - These currents depend on the - IE4 = Super premium efficiency
rated operational current of the starter (Ie AC-3) and are given - IE3 = Premium efficiency
by the standard (Table 13). - IE2 = High efficiency
For example: - IE1 = Standard efficiency
- r = 1kA for Ie AC-3 < 16 A • Motor design N/H and NE/HE
- r = 3 kA for 16 A < Ie AC-3 < 63 A IEC 60034-12:2016 standard defines motor design categories
- r = 5 kA for 63 A < Ie AC-3 < 125 A etc. as below:
• at the rated conditional short-circuit current "Iq" - This is the - Design N
Normal starting torque with normal locked rotor current
maximum prospective current that the combination can with-
stand, for example 50 kA. - Design H
High starting torque with normal locked rotor current
- Design NE
Normal starting torque with higher locked rotor current
- Design HE
High starting torque with higher locked rotor current.

13

1SBC101590S0201 - Rev. B