Table of Contents
Advertisement
3 Mounting and Commissioning
In secondary values:
with
N
N
If substantial deviations or wrong the sign occur, then the voltage transformer connec-
tions are incorrect.
After shutdown and de-excitation of the generator, and removal of the short-circuit
bridge, the short-circuit tests are completed. No further tests are required for unbal-
anced load protection, overcurrent time protection, thermal overload protection
and impedance protection.
Activate the overcurrent time protection and the impedance protection (address 1201:
O/C I> = ON or address 1401 O/C Ip = ON, address 3301: IMPEDANCE PROT. =
ON) and it works immediately as a short-circuit protection for all subsequent tests. If
used, address 1301 O/C I>> = ON, the thermal overload protection (address 1601:
Ther. OVER LOAD = ON), the unbalanced load protection (address1701:
UNBALANCE LOAD = ON) can be activated. Otherwise, they are set to Off.
3.3.9
Checking the Voltage Circuits
General
The voltage circuits of the machine are checked to ensure the correct cabling, polarity,
phase sequence, transformer ratio etc. of the voltage transformers - not to check indi-
vidual protection functions of the device.
Earthing of the
When checking the voltage transformers, particular attention should be paid to the
Voltage Transform-
broken delta windings because these windings may only be earthed in one phase.
ers
Preparation
Set the overvoltage protection function to about 110 % of the rated generator voltage
with trip on excitation.
Switch frequency protection (address 4201) and overexcitation protection (address
4301) to Block relay.
Check in the unexcited condition of the machine with the help of remanent voltages,
that all short-circuit bridges are removed.
Test Instruction
The checks of all voltage transformer circuits (protection, measuring, metering etc.)
are carried out with about 30 % of the rated transformer voltage. Tests with generator
voltages of more than 30 % rated voltage are only required when the idle characteristic
is measured for the first time.
The measuring circuit supervision of the rotor earth fault protection (see below) can be
checked when testing the voltage circuits, or after the synchronization.
274
CTR
VTR
- Current transformer ratio
- Voltage transf. transform. ratio
7UM61 Manual
C53000-G1176-C127-3
Advertisement
Table of Contents
