Mounting and Commissioning
3.3 Commissioning
SIPROTEC, 7UM62, Manual
C53000-G1176-C149-7, Release date 03.2010
433
Check Using Network Earth Fault
With the primary plant voltage-free and earthed, install a single-pole earth fault bridge on the high voltage side
of the unit transformer.
DANGER!
Primary measurements may only be carried out with the generator at stand–still on disconnected and grounded
equipment of the power system.
Caution!
Possible starpoint earthing at transformer with simultaneous earthing on high voltage side during test!
Nonobservance of the following procedures can result in minor injury or material damage.
The starpoints of the unit transformer must be disconnected from earth during this test!
Start up machine and slowly excite to 30 % of rated machine voltage.
Read out under operational measured values: U
E
This value is extrapolated to rated machine voltage (Figure
3-35). The fault value thus calculated should correspond, at the most, to half the pickup value U0> (address
5002), in order to achieve the desired safety margin.
Shut down and de-excite the generator. Remove earth fault bridge.
If the starpoint of the high-voltage side of the unit transformer is to be earthed during normal operation,
re-establish starpoint earthing now.
Activate the stator earth fault protection: set address 5001 S/E/F PROT. to ON. If the sensitive earth fault de-
tection is used for stator earth fault protection, activate it as well: set address 5101 O/C PROT. IEE to ON.
Busbar Connection
Firstly, the correct functioning and data of the loading equipment must be checked: sequencing, time limit, etc.,
as well as the plant data: Earthing transformer and the value of the load resistor (tapping).
Switch rotor earth fault protection (address 5001) to Block relay. If the sensitive earth fault detection is used
for stator earth fault protection, switch it to Block relay also under address 5101.
With the primary plant earthed and voltage-free, install a single pole earth fault bridge between generator ter-
minals and toroidal current transformer (see the following Figure).
DANGER!
Primary measurements may only be carried out with the generator at stand–still on disconnected and grounded
equipment of the power system.
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