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Functional Tests
9.9 Protection Functional Tests
78VS Voltage Vector Shift
9.9.25
Vector shift is a 3 phase protection and therefore test voltages must be applied to all 3 VT inputs. Elements
with the highest pick-up setting should be tested first. The elements with lower pick-up settings can then be
tested without the need to disable the elements already tested.
To test operation of the 78 elements, it is necessary to apply a step change to the phase angle i.e. a 'jump' in
the voltage waveform. The size of the jump is increased with each test step until the element operates. Being
instantaneous, there is no difference between the element picking-up and operating. Therefore the 78-n
output contact can be used for both pick-up and timing measurements.
Voltage Vector
Shift (°)
The applied voltage must be above the 78 UV Guard (Ph-N) setting in the Vector Shift menu for the
element to operate. This setting can be tested by applying the test voltage at a level below the 78 U/V Guard
setting at a vector shift in the operate range. Increase the voltage until the relay operates.
UVG Setting (Volts) Vector Shift
Check correct indication, trip output, alarm contacts, waveform record.
Element Blocking
The vector shift elements can be blocked by Binary Input Inhibit. This functionality should be checked.
Element
78-1
78-2
When testing is complete reinstate any of the disabled functions.
81 Frequency Protection – "f>" or "f<"
9.9.26
Elements can be mapped to operate for frequency measurement on the 3 phase voltage inputs or the single
phase input V4. The 3 phase function can be tested by application of 1P or 3P voltage. For over-frequency, the
elements with the highest setting should be tested first and for under-frequency the elements with the lowest
settings should be tested first. The elements with other settings can then be tested without need to disable
the elements already tested. Note that the relay is designed to track the gradual changes in power system
frequency and that sudden step changes in frequency during testing do not reflect normal system operation.
Normal, instantaneous, operation of the frequency element is 140 ms to 175 ms in line with the Technical
Data. Application of sudden step changes to frequency can add additional delay which can produce
misleading test results.
Gradually increase/decrease applied voltage frequency until 81-n operation occurs. Elements set for more
extreme frequency fluctuation should be tested first with lesser elements disabled.
If the 81-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 should then be gradually decreased/increased until the element resets. The reset frequency can
be used to check the Hysteresis setting.
Apply setting frequency +0.5 Hz for over-frequency or -0.5 Hz 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.
494
P.U. Phase Step (°)
Operate Time (s)
Blocked Vector
Element Used for
Shift (D.O.)
Test
UV Guard
Unblocked Vector
Shift (P.U.)
BI Inhibits
Reyrolle 7SR5, Overcurrent Protection Device, Device Manual
C53000-G7040-C014-1, Edition 11.2019
Notes
Notes
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