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The frequency should then be gradually decreased/increased until the element resets. The reset frequency can
be used to check the Hysteresis setting.
If the element is set as 81-n U/V Guarded, The applied voltage must be above the 81 UV Guard Setting in the
U/O Frequency menu.
Apply setting frequency +0.5Hz for Over-frequency or -0.5Hz for Under-frequency and record operating time.
Starting with the element in the operated condition, gradually increase or decrease the applied voltage until the
element resets. Measure the reset voltage level to check the 81 Hysteresis setting.
F
U/O
DTL
(Hertz)
(sec)
If the element is set as 81-nU/V Guarded, this setting can be tested by applying the test voltage at a level below
the 81 U/V Guard Setting at a frequency in the operate range. Increase the voltage until the relay operates.
UVG
UVG Setting
(Volts)
U/O Freq
2.11.1.1
Element Blocking
The U/O Frequency elements can be blocked by Binary Input Inhibit. This functionality should be checked.
Element
Check correct indication, trip output, alarm contacts, waveform record.
When testing is complete reinstate any of the disabled functions.
©2010 Siemens Protection Devices Limited
Hyst.
D.O.
P.U.
(calc.)
Freq
Hertz
Freq element
Used for test
Volts (D.O.)
81-1
81-2
81-3
81-4
81-5
81-6
7SR242 Duobias Commissioning & Maintenance Guide
D.O.
Operate
Freq.
Time
Hertz
+/- 0.5Hz
Blocked
Unblocked Volts (P.U.)
BI Inhibits
UV
NOTES
Guard
NOTES
Chapter 6 Page 44 of 57
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