TM-DC Thermal-Magnetic Trip Unit for 3P and 4P Circuit Breakers from 80 A to 250 A

Introduction

The TM-DC thermal-magnetic trip unit for 3P/4P circuit breakers from 80 A to 250 A are interchangeable trip units.

They are designed for DC general-purpose applications.

The TM-DC 3P/4P trip units provide:

• adjustable thermal threshold

• fixed magnetic pick-up on trip units with In from 80 A to 160 A

• adjustable magnetic pick-up on trip units with In 200 A and 250 A

Description

The setting range and adjustment dials are on the front of the trip unit.

A Setting range for TM-DC thermal-magnetic 3P/4P trip unit

B Adjustment dial for the thermal protection pick-up Ir

C Adjustment dial for the magnetic protection pick-up Ii (for TM-DC 200/250 only)

Setting the Thermal Protection

The thermal protection pick-up Ir is set by a 4-setting dial.

Turning the thermal protection adjustment dial (A) modifies the trip curve as shown (B).

The following table shows the values of the pick-up Ir (in amperes) for thermal protection (values indicated on the dial) with respect to every trip unit rating, relative to the position of the dial Ir.

Setting the Magnetic Protection on Trip Units With In from 80 A to 160 A

For trip units rated below 200 A, the magnetic protection pick-up cannot be adjusted and equals the value shown below:

Setting the Magnetic Protection on Trip Units With In 200 A and 250 A

For trip units rated between 200 A and 250 A, the magnetic protection pick-up Ii is set by a 6-setting dial.

Turning the magnetic protection adjustment dial (A) modifies the trip curve as shown (B).

The following table shows the values of the pick-up Ii (in amperes) for magnetic protection (values indicated on the dial), relative to the position of the Ii dial: