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3.3.11 Checking the Sensitive Earth Fault Protection when Used for Rotor Earth Fault
Protection
If the sensitive earth fault protection is used for rotor earth fault protection, it must first
be set to 5101 under address O/C PROT. Iee> Block relay.
Caution!
A rotor circuit not isolated from earth can result in a double fault in conjunction with an
earth resistor inserted for checking purposes!
Nonobservance of the following procedures can result in minor injury or material
damage.
Make sure that the checked rotor circuit is completely isolated from the earth, to avoid
the earthing resistor interposed for test purposes causing a double earth fault!
An earth fault is simulated via a resistor which is roughly equivalent to the desired trip
resistance. In generators with rotating rectifier excitation, the resistor is placed
between the two measurement slip rings; in generators with excitation via slip rings
between one slip ring and earth.
Start up generator and excite to rated voltage. If applicable place measurement
brushes into operation. It is irrelevant in this context whether the sensitive earth fault
protection picks up or not. The earth fault current IIEE now flowing can be read out on
the protection device under the operational measured values.
Check that this measured earth fault current is roughly equal to the pickup value 5102
for sensitive earth fault detection that has been set in address IEE>. However it must
not be set to less than double the value of the spill current that has been determined
for healthy insulation.
For generators with excitation via slip rings, the test is repeated for the other slip ring.
Shut down generator. Remove earth fault resistor.
The sensitive earth fault detection used for rotor earth fault protection is then activat-
ed: O/C PROT. Iee> = ON in address 5101.
3.3.12 Tests with the Network
Checking the
The following test instructions apply to a synchronous generator.
Correct Connection
Start up generator and synchronize with network. Slowly increase driving power input
Polarity
(up to approximately 5%).
The active power is read out under the operational measured values (percent values)
as a positive active power P in percent of the rated apparent power S
If a negative power value is to be displayed, direction allocation between the CT set
and the voltage transformer set does not correspond with the configuration under
address 210 (CT Starpoint = towards machine or towards starpt.), or con-
figuration of address 1108 (ACTIVE POWER = Generator or Motor) is not properly
selected. Address 210 is to be reconfigured, as the case may be.
7UM61 Manual
C53000-G1176-C127-3
3.3 Commissioning
.
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