General Notes - Siemens UL 489 Operating Instructions Manual

25.1

General Notes

A few facts about WL trip units and breakers will help the tester understand how best to accomplish the required testing quickly and easily.
Air Core Sensor Technology
WL Breakers are equipped with air-core current sensors (Rogowsky coils, also known as linear couplers) and, as such, the ETUs cannot be
tested by conventional secondary injection techniques.
Ground Fault Protection
WL Breaker trip units can be equipped with ground fault protection according to the table below. Ground fault protection cannot be disabled
if it has been installed at the factory. Setting the Ground Fault Mode is either done via switch (see below) or via menu
ETU Type
ETU 745
ETU 755 / 776
Figure 1
Ground Fault Mode Switch
Ground Fault Trip
Pick-up Adjustment
The ground fault pick-up points for the Ground Fault Alarm and Ground Fault Trip settings are independently configurable. The definitions of
the A - E dial settings are described below:
Available Ground Fault Modes
Optional: 3 or 4 wire residual, and direct sensing, are both available with additional
ground fault protection module. Mode is set by switch.
Optional: 3 or 4 wire residual, and direct sensing, are both available with additional
ground fault protection module. Mode is set by soft setting.
Ground Fault Alarm
Pick-up Adjustment
Pick-up Setting Frame Size 1
A 100 A
B 300 A
C 600 A
D 900 A
E 1200 A
Ground Fault Trip
Delay Adjustment
Frame Size 2 Frame Size 3
100 A 400 A
300 A 600 A
600 A 800 A
900 A 1000 A
1200 A 1200 A
(page 9-44).
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