Siemens Reyrolle 7SR5 - Voltage Dependent Overcurrent - Phase

51V Voltage Dependent Overcurrent – Phase
OC Phase Control Voltage
CT1(I
A
) V
12
(V
AB
)
CT2(I
B
) V
23
(V
BC
)
CT3(I
C
) V
31
(V
CA
)
IDMT Phase Overcurrent elements 51-n should be tested for pick-up and timing before this function is
tested. The General Pickup LED can be used to assess operation of this function if other functions are disa-
bled or if the setting allocating General Pickup is temporarily modified.
Apply nominal 3 phase balanced voltage. Apply 3 phase balanced current at a level below the normal 51-n
setting but above the effective 51V-n setting. Ensure that the thermal rating of the relay is not exceeded.
Gradually reduce the voltage until the a-b voltage is less than the Voltage setting. Pickup LED operation
can be used to confirm the Voltage setting. If the 51V-n current setting is above the continuous rating of the
relay an alternative procedure should be used, apply test current in short duration shots with applied voltage
being gradually reduced for each subsequent shot.
Apply nominal 3 phase balanced voltage. Increase the voltage such that the a-b voltage is 110 % of the
Voltage setting. Test current can be applied as 3 phase balanced current or as a single phase a-b current via
CT1 and returning through CT2. Gradually increase the a-b phase current or balanced 3P current until Pickup
LED operates. Confirm result of phase O/C test above.
Reduce the applied voltage to a level such that VAB phase-phase voltage is less than 90 % of the setting. The
element threshold is operated by phase to phase voltage but the most common connection of the 3 phase
voltage inputs is phase to neutral.
Gradually increase the CT1 phase-phase current until Pickup LED operates.
Note that these elements may be set as directional. If this is the case, the phase angle of the current must be
set with respect to the voltage to produce operation of the elements.
Voltage Setting (V, p-p)
Measured (V, p-p)
I Setting Multiplier Calculated PU Measured Tolerance
51-1 Pickup
51-2 Pickup
51-3 Pickup
51-4 Pickup
Element Blocking
The Voltage Controlled Overcurrent function can be set to Inhibit for VT Supervision operation.
This functionality should be checked. Apply balanced voltage and current. Reduce a-phase voltage to cause a
VTS condition. Increase 3P current until the element operates at its full setting, i.e. 51V settings are not used.
Element
VTS Action
51-1
51-2
51-3
51-4
Check correct indication, trip output, alarm contacts.
9.10.15
Functional Tests
9.10 Protection Functional Tests
440 Reyrolle 7SR5, Transformer Protection Device, Device Manual
C53000-G7040-C015-1, Edition 11.2019