MicroLogic 1.3 M Electronic Trip Unit

Introduction

The MicroLogic 1.3 M electronic trip unit with high short-time protection pickup provides motor-feeders with short-circuit protection. Two ratings are available, 320 A and 500 A.

Use the MicroLogic 1.3 M electronic trip unit to create a type 1 or type 2 coordination motor-feeder.

Description

The adjustment dial and indication are on the front face.

A MicroLogic trip unit rating

B Adjustment dial for the short-time protection pickup Isd

C Instantaneous protection pickup Ii

D Test port

E Ready LED (green)

Setting the Short-Time Protection

Set the short-time protection pickup Isd using a 9-setting dial.

Turning the pickup Isd adjustment dial (A) modifies the curves as shown (B).

The following table shows the values of the pickup Isd (in amperes) for short-time protection (values indicated on the dial) relative to the position of the Isd dial and the values of the pickup Ii for instantaneous protection.

Trip unit rating In	Pickup Isd (A)									Pickup Ii (A)
320 A	1600	1920	2240	2560	2880	3200	3520	3840	4160	4800
500 A	2500	3000	3500	4000	4500	5000	5500	6000	6500	6500

The precision range is +/- 15%.

Example of Application

The following is an example of a motor-feeder application:

Power supplied by a 1,250 kVA transformer, 400 V, 4%
Downstream power supply of a motor-feeder with the following characteristics:
- 3-component motor-feeder (circuit breaker, thermal relay, contactor)
- Direct-on-line starting
- Motor power 160 kW (In = 280 A)
- Type 2 coordination

Installation diagram:

Use calculations performed on the installation in accordance with the regulations to determine the characteristics of the appropriate ComPact NSX circuit breakers to install (calculations performed using the Ecostruxure Power Design – Ecodial software).

Circuit breaker selection

Installation	Circuit breaker	Comments
In = 280 A	ComPact NSX400 with MicroLogic 1.3 M 320	Motor circuit breaker, case size
Isc = 28.5 kA	F	Read the Icu performance from faceplate label
Ik min = 18.3 kA	–	–

Trip unit protection

Installation	Trip unit setting	Comments
Ik min = 18.3 kA Inrush current = 14 In	Isd = 4,160 A	The Isd protection setting is compatible with: Transient startup currents Short-circuit protection

Installation

Trip unit setting

Comments

Ik min = 18.3 kA

Inrush current = 14 In

Isd = 4,160 A

The Isd protection setting is compatible with:

Transient startup currents
Short-circuit protection