Protection for Motor-Feeders

Introduction

TeSys GV5 / GV6 devices:

• Provide protection for direct-on-line motor-feeders and star-delta motor starters (direct-on-line starting is the most widely used type of motor-feeder).

• Integrate the basic protections (overload, short-circuit, and phase unbalance) for the motor-feeder.

• Allow protection and coordination of the motor-feeder components that comply with the requirements of IEC/EN 60947-2 and IEC/EN 60947-4-1 standards.

• Are used to create motor-feeders with two devices.

A TeSys GV5 / GV6 device B Instantaneous protection C Overload protection D Contactor E SDTAM thermal fault module

Characteristics Defined by IEC/EN 60947-4-1 Standard

A motor-feeder must satisfy the general rules of IEC/EN 60947-4-1 standard, in particular the rules concerning the protection of contactors and motor-feeders.

In the matter of protection, this standard defines:

• Coordination of motor-feeder protections

• Trip class setting value

• Insulation coordination

Coordination According to IEC/EN 60947-4-1 Standard

Two types of coordination are allowed: type 1 coordination or type 2 coordination.

• In type 1 coordination, deterioration of the contactor and relay is accepted under the two following conditions:

  • The contactor or starter does not represent a danger to people or installations.

  • The starter can operate correctly when parts have been repaired or replaced.

• In type 2 coordination, some slight welding of the contactor or starter contacts is allowed if, following type 2 coordination tests:

  • They are easy to separate.

  • The control and protection switchgear functions then work without the need for repair.

To ensure type 2 coordination, IEC/EN 60947-4-1 standard lays down three Id fault current tests intended to check that the equipment behaves correctly in overload and short-circuit conditions.

1 Overload zone Id < 10 In 2 Impedant short-circuit zone 10 In < Id < 50 In 3 Short-circuit zone Id > 50 In