Undervoltage Guard (27/59Uvg) - Siemens 7SR242 Duobias Commissioning And Maintenance Manual

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7SR242 Duobias Commissioning & Maintenance Guide

2.9.2 Undervoltage Guard (27/59UVG)

If any 27 Undervoltage element is set to be inhibited by the 27 Undervoltage Guard element, this function should

be tested.

Connect the test voltage inputs to suit the installation wiring diagram utilising any test socket facilities available. It

may be useful to temporarily map an LED as 'General Pickup' to assist during testing. 27UVG operation will reset

the General Pickup if no other element is operated. This LED should not be set as 'Hand Reset' in the Output

matrix.

Starting from nominal voltage, apply a step decrease to the applied voltage to a level below the 27 Undervoltage

setting but above the 27UVG setting such that an Undervoltage element operation occurs. Slowly reduce the

applied voltage until the 27 Undervoltage element resets, this can be detected by the General Pickup LED reset if

no other element is operated (this includes any Undervoltage element which is not UV Guarded).

Phase

V element

Blocked

NOTES

(Volts)

Used for test

Volts

UVG

Chapter 6 Page 40 of 57

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