Frequency Protection - "Df/Dt - Siemens 7SR51 Device Manual

Freq U/O
(Hertz)
Element Blocking
The U/O frequency elements can be blocked by Binary Input Inhibit. This functionality should be
checked.
Element
81-1
81-2
81-3
81-4
81-5
81-6
Check correct indication, trip output, alarm contacts, waveform record.
When testing is complete reinstate any of the disabled functions.
81R Frequency Protection – "df/dt"
9.9.27
This function is applied to the 3 phase voltages but can be tested by application of only 1P or all 3P voltages.
Check Phase Voltage Config setting to identify correct voltage inputs for test voltage application.
Elements with the highest ROCOF pickup setting should be tested first. The elements with lower pickup
settings can then be tested without need to disable the elements already tested. The applied phase voltage
must be above 19 V for the element to operate. Tests should be applied at rated voltage.
Gradually increase/decrease applied voltage frequency gradient until 81R-n operation occurs. If the 81R-n
Delay setting is long it will be advantageous to map the function to temporarily drive the relevant pickup
output in the Pickup Config sub-menu in the Output Config menu as this will allow the Pickup LED to
operate for the function. If the delay setting is short the operation of the element can be easily checked
directly.
The frequency gradient should then be gradually decreased/increased until the element resets.
Apply voltage frequency gradient at twice setting level and record operating time.
ROCOF (Hz/s) Dir
Check correct indication, trip output, alarm contacts, waveform record.
Element Blocking
The ROCOF elements can be blocked by Binary Input Inhibit. This functionality should be checked.
Element
81R-1
81R-2
81R-3
81R-4
81R-5
81R-6
When testing is complete reinstate any of the disabled functions.
Reyrolle 7SR5, Overcurrent Protection Device, Device Manual
C53000-G7040-C014-1, Edition 11.2019
Delay Hyst. D.O.
(sec) (calc.)
Delay (sec) P.U. ROCOF
(Hz/s)
P.U. Freq D.O. Operate
(Hz) Freq. Time @ ±
(Hz) 0.5 Hz
BI Inhibits
D.O. ROCOF Operate Time
(Hz/s) @ 2 ⋅ setting
BI Inhibits
Functional Tests
9.9 Protection Functional Tests
UV Notes
Guard
Notes
495