Siemens Siprotec 7UM611 User Manual

3 Mounting and Commissioning
286
7UM61 Manual
C53000-G1176-C127-3
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); ob-
serving for this 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 su-
pervision (address 3201) switched to Off. For motors this and the following measure-
ments 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 motoring power values because of possible
angle errors of the current and voltage transformers. The motoring power/reactive
power curve then would not be a straight line parallel with the real power axis of 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 sen-
sitive.
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.
Caution!
Underexcitation may cause the generator fall out of step!
Nonobservance of the following procedures can result in minor injury or material
damage.
Operation with underexcitation is admissible only for a short period
Proceed as follows:
• Adjust excitation until the reactive power Q = 0. To check this, read out the active
power P
0
and the reactive power Q
0
with sign and note it down (see table below).
• Slowly increase excitation to 30% of rated apparent power of generator (overexcit-
ed).
– Read out the motoring power P
1
with polarity (negative) in the operational mea-
sured values and note it (see table below).
– Read out the reactive power Q
1
with polarity (positive) and note it (see table
below).
www . ElectricalPartManuals . com

Siemens Siprotec 7UM611 Specifications

General

Brand	Siemens
Model	Siprotec 7UM611
Category	Relays
Language	English