Checks With The Network - Siemens SIPROTEC 7UM62 Manual

3.3.21

Checks with the Network

Note
Since the protective function adjusts the scanning frequency, the test requires that a nominal-frequency phase-
to-earth voltage (e.g. U
Checking the Correct Connection Polarity
The following test instructions apply to a synchronous generator.
Start up generator and synchronize with network. Slowly increase driving power input (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 displayed, allocation direction between the CT set of side 2 and the voltage trans-
former set does not correspond with the configuration under address 210 (STRPNT->OBJ S2: YES/NO), or the
configuration of address 1108 ACTIVE POWER = Generator or Motor) is not properly selected. Address 210
is to be reconfigured, as required.
If the power continues being incorrect, there must be an error in the transformer wiring (e.g. cyclical phase
swap):
• Remedy faults of the transformer lines (current and/or voltage transformers) observing the safety rules,
• Repeat test.
Measurement of Motoring Power and Angle Error Correction
Leave the reverse power protection (address 3101) and the forward active power supervision (address 3201)
switched to Off for now. For motors, this and the following measurements are not required.
Independent of the excitation current of the generator, i.e. of the reactive power Q, the motoring power is – as
an active power – practically constant. However, the protection device may detect and display different motor-
ing power values because of possible angle errors of the current and voltage transformers. The motoring pow-
er/reactive power curve then would not be a straight line parallel with the abscissa (active Power = 0) in the
machine power diagram. Therefore, the angle deviations should be measured at three measuring points and
the correction parameter W0 established. The angle errors caused by the device internal input transformers
have already been compensated in the factory. This check is recommended if the reverse power protection is
set to sensitive.
Reduce driving power to zero by closing the regulating valves. The generator now takes motoring energy from
the network.
Caution!
Overheating on input of reverse power by the generator
Operating the turbine without a minimum steam throughput (cooling effect) can cause the turbine blades to
overheat!
Input of reverse power is admissible with a turboset only for a short period.
SIPROTEC, 7UM62, Manual
C53000-G1176-C149-7, Release date 03.2010
) is injected at least at one voltage input.
L1
.
N
Mounting and Commissioning
3.3 Commissioning
443