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3 Mounting and Commissioning
Check Using
With the primary plant voltage-free and earthed, install a single-pole earth fault bridge
Network Earth Fault
on the primary side of the unit transformer.
DANGER!
Energized equipment of the power system ! Capacitive coupled voltages at discon-
nected equipment of the power system !
Non-observance of the following measure will result in death, severe personal injury
or substantial property damage.
Primary measurements must only be carried out 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
machine voltage (see example in Figure 3-18). 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.
Activate the stator earth fault protection: Address 5001 S/E/F PROT. = ON. If the
sensitive earth fault detection is used for stator earth fault protection, activate it as well:
Address 5101 O/C PROT. Iee> = ON.
Busbar Connection
Firstly, the correct functioning and data of the loading equipment must be checked: se-
quencing, 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 5101 also
under address Block relay.
With the primary plant earthed and voltage-free, install a single pole earth fault bridge
between generator terminals and toroidal current transformer (see the following Fig-
ure).
280
This value is extrapolated to rated
E
7UM61 Manual
C53000-G1176-C127-3
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