GE 745 Instruction Manual page 205

CHAPTER 5: SETPOINTS
CAUTION
745 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
are entered as setpoints. When placed in simulation mode, the relay suspends reading
actual AC inputs and generates samples to represent the programmed phasors. These
samples are used in all calculations and protection logic. Enabling this feature will turn off
the In Service LED, turn on the Test Mode LED, and de-energize the self-test relay.
When in simulation mode, protection features do not operate based on actual system
inputs. If simulation mode is used for field testing on equipment, other means of
protection must be provided by the operator.
• SIMULATION FUNCTION: Select the simulation mode required. Select "Disabled" to
return the 745 to normal operation. The following table details the simulation function
modes.
– "Prefault Mode": Select
of a transformer. In this mode, the normal inputs are replaced with sample values
generated based on the programmed prefault values. Phase currents are
balanced (i.e. equal in magnitude and 120° apart), and the phase lag between
windings is that which would result under normal conditions for the transformer
type selected. The magnitude of phase currents for each winding are set to the
values programmed in
W1(3) PHASE ABC CURRENT MAGNITUDE
the value programmed in
VOLTAGE INPUT MAGNITUDE
SYSTEM SETUP

– "Fault Mode": Select fault mode to simulate the faulted operating condition of a
transformer. In this mode, the normal inputs are replaced with sample values
generated based on the programmed fault values. The magnitude and angle of
each phase current and ground current of the available windings, the magnitude
and angle of the voltage input, and system frequency are set to the values
programmed under
A logic input, programmed to the "Simulate Fault" function, can be used to trigger the
transition from the "Prefault Mode" to the "Fault Mode", allowing the measurement of
element operating times.
– "Playback Mode": Select
file which has been pre-loaded into the relay. In this mode, the normal inputs are
replaced with 32 cycles of waveform samples downloaded into the 745 by the
EnerVista 745 Setup software (from an oscillography data file in the IEEE
COMTRADE file format).
A logic input, programmed to the "Simulate Playback" function, can be used to trigger
the transition from the "Prefault Mode" to the "Playback Mode", allowing the
measurement of element operating times.
• BLOCK OPERATION OF OUTPUTS: Select the output relays which must be blocked
from operating while in simulation mode. An operator can use the simulation feature
to provide a complete functional test of the protection features, except for the
measurement of external input values. As this feature may be used for on site testing,
provision is made (with this setpoint) to block the operation of output relays during this
testing, to prevent the operation of other equipment. Note that the default setting
blocks the operation of all output relays.
• START FAULT MODE SIGNAL: Select any logic input which, when asserted, initiates
fault mode simulation. This signal has an effect only if the 745 is initially in prefault
mode.
to simulate the normal operating condition
prefault mode
S6 TESTING SIMULATION

. The magnitude of the voltage is set to
S6 TESTING SIMULATION

. The frequency is set to the value programmed in
TRANSFORMER NOMINAL FREQUENCY

S6 TESTING SIMULATION

to play back a sampled waveform data
playback mode
S6 TESTING
PREFAULT VALUES
 
PREFAULT VALUES

.
.
FAULT VALUES


S2
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