32 Power Protection - Siemens 7SR51 Device Manual

Single phase voltage should be connected to the Vx input directly. If the DTL is short, starting from nominal
voltage, slowly decrease the applied test voltage until the Pickup LED (temporarily mapped) is on. Record the
operate voltage. The LED should light at setting Volts ± 5 %. Slowly increase the input voltage until the LED
extinguishes. Record the reset voltage to check the Hysteresis setting. If the DTL is long, the operate level
should be checked by applying a voltage of 90 % of setting voltage. Check hysteresis by resetting element to
the operate level setting plus the Hysteresis setting.
Connect the relevant output contact(s) to stop the test set. Step the applied voltage to a level below the
setting. The test set should be stopped at the operate time setting ± 5 %.
When testing is complete reinstate any of the disabled functions.
Setting DTL (sec)
(Volts)
Element Blocking
The Vx Under Voltage elements can be blocked by Binary Input Inhibit. This functionality should be
checked.
Element
27-1
27-2
Check correct indication, trip output, alarm contacts, waveform record.
When testing is complete reinstate any of the disabled functions.
Undervoltage Guard
If any Vx undervoltage element is set to be inhibited by the UV Guard element, this function should be
tested.
Connect the test voltage inputs to suit the installation wiring diagram utilizing any test socket facilities avail-
able. It may be useful to temporarily map an LED as General Pickup to assist during testing. UV Guard
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 27Vx under-
voltage setting but above the 27Vx UV Guard setting such that an undervoltage element operation occurs.
Slowly reduce the applied voltage until the 27Vx 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
Vx UVG

32 Power Protection

9.9.4
This function can be tested by application 3P current and voltage. For over-power, the elements with the
highest setting should be tested first and for under-power 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.
From the nominal power setting S
tion occurs. In general it is most convenient to apply balanced rated voltage and increase or decrease current
on 1 or 3 phases. The thermal withstand limitations of the current inputs and overvoltage limitations of
voltage inputs, stated in the Technical Data should always be observed throughout testing. This will avoid
trigger of VTS which may be configured to block 32 power elements, usually only underpower.
Reyrolle 7SR5, Overcurrent Protection Device, Device Manual
C53000-G7040-C014-1, Edition 11.2019
Hyst. D.O.
(calcu-
lated)
Setting (Volts) Tolerance
gradually increase/decrease applied voltage or current until 32-n opera-
rated
P.U. Volts D.O Volts Op. Time
@ 0.5 ⋅ V
(UV)
BI Inhibits
V Element Used Blocked Volts
for Test
Functional Tests
9.9 Protection Functional Tests
UV Guard Tolerance
set
Notes
467