Mounting and Commissioning
3.3 Commissioning
SIPROTEC, 7UM62, Manual
C53000-G1176-C149-7, Release date 03.2010
441
Check the operational measured value Rearth and the pickup indication („REF 1-3Hz Fault“) and, after T-
TRIP-RE<< (10 s on delivery) has expired, check the trip indication („REF 1-3Hz Trip“).
Set the resistance to approx. 90 % of the warning stage (address 6102 RE< WARN), read out the operational
measured value „Re =“, and check the warning message („REF 1-3Hz Warn“). If there is heavy inter-
ference from the excitation system, it may be necessary to reduce the high-omic resistance set for the warning
threshold.
Remove the earthing resistor and check the operational measured values as well as the measuring circuit su-
pervision „REF 1-3Hz open“ under fault-free conditions. If spontaneous indications are issued by the mea-
suring circuit monitoring, reduce the pickup value (address 6106 Qc <) or deactivate the monitoring.
For generators with excitation via slip rings, the test is repeated for the other slip ring.
Shut down generator. Remove earth fault resistor.
Activate the rotor earth fault protection: REF 1-3Hz = ON in address 6101.
3.3.20 Checking the Interturn Fault Protection
Switch the interturn fault protection (address 5501) to Block relay.
Asymmetries in the stator windings impair the sensitivity of the protection. The two-pole fault is particularly crit-
ical in this context.
Caution!
Even fault currents which are significantly smaller than the nominal current can thermally endanger the gener-
ator due to the unbalanced load (negative sequence current)!
First, the maximum permissible fault current has to be determined.
If the generator is excited using nominal current, the following negative sequence currents are obtained as a
result:
Single-pole fault Two-pole fault
100/3 = 33,3 % 100/√3 = 57,7 %
If, for instance, the permanently admissible unbalanced load current is 11 %, the following generator currents
must not be exceeded:
Single-pole fault Two-pole fault
11 %/33,3 % · I
NG
= 0.33 I
NG
11 %/57,7 % · I
NG
= 0.19 I
NG
selected 0.3 I
NG
selected 0.17 I
NG
The same percentages apply to the excitation current.
Install a two-pole short-circuit bridge, which can also conduct fault currents, at the generator terminals.
DANGER!
Primary measurements may only be carried out with the generator at standstill on disconnected and earthed
equipment of the power system.
Run up machine until it has reached permissible excitation and measure the excitation current and the displace-
ment voltage at the device under the operational measured values.
To Next Page
Loading...
Need help?
General
