CHAPTER 5: SETTINGS
469 MOTOR MANAGEMENT RELAY – INSTRUCTION MANUAL
5–21
Enter the nominal system frequency here. These settings allow the 469 to determine the
internal sampling rate for maximum accuracy.
The 469 may be used on variable frequency drives when the
NOMINAL SYSTEM FREQUENCY
is set to “Variable”. All of the elements function in the same manner with the following
exceptions:
•
If the ratio of the smallest phase RMS to largest phase RMS is more than 70%,
CURRENT UNBALANCE
is calculated from the ratio of phase current RMS values. Phase
angles are ignored. With nominal sinusoidal phase inputs, this method produces
values about two times the value produced by calculating I
1
/I
2
.
•
If the ratio of the smallest phase RMS to largest phase RMS is less than 70%, a fixed
value 40%
CURRENT UNBALANCE
is used. Derating still applies when the average load
is less than FLA.
The voltage and power elements work properly if the voltage waveform is approximately
sinusoidal. An unfiltered voltage waveform from a pulse width modulated drive cannot be
measured accurately; however, the current waveform is approximately sinusoidal and can
be measured accurately. All current elements will function properly. Note, however, that
undervoltage and underfrequency elements will not work instantaneously using variable
frequency. If “Variable” is chosen, the filtering algorithm increases the trip and alarm times
by up to 270 ms when the level is close to the threshold. If the level exceeds the threshold
by a significant amount, trip and alarm times will decrease until they match the
programmed delay. The exceptions to this increased time are the short circuit, ground
fault, and differential elements which will trip as per specification.
If the sequence of phase rotation for a given plant is ACB rather than the standard ABC, the
SYSTEM PHASE SEQUENCE
settings may be used to accommodate this. This settings allows
the 469 to properly calculate phase reversal, negative sequence, and power quantities. The
SPEED2 PHASE SEQUENCE
can be programmed to accommodate the reversed motor
rotation at Speed2 and is seen only if two-speed motor protection is enabled.
5.3.4
Communications Control
PATH: SETTINGS
S2 SYSTEM SETUP
SERIAL COMM. CONTROL
If enabled, motor starting and stopping is possible via any of the three 469 communication
ports. Refer to GE publication GEK-106491:
469 Communications Guide
for command
formats. When a stop command is issued, the 1 TRIP relay is activated for 1 second to
complete the trip coil circuit for a breaker application or break the contact coil circuit for a
contactor application. When a start command is issued, the auxiliary relay assigned for
starting control is activated for 1 second to complete the close coil circuit for a breaker
application or complete the start control circuit for a contactor application. A contactor
sealing contact would be used to maintain the circuit.
For details on issuing a start or stop command via communications, refer to GE publication
GEK-106491:
469 Communications Guide
.
SERIAL COMM. [
]
CONTROL
SERIAL COMMUNICATION
CONTROL: Off
Range: On, Off
MESSAGE
ASSIGN START CONTROL
RELAYS: Auxiliary2
Range: Auxiliary2, Aux2 & Aux3,
Auxiliary3
Summary of Contents for Masoneilan 469 Series
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Page 92: ...3 28 469 MOTOR MANAGEMENT RELAY INSTRUCTION MANUAL CHAPTER 3 INSTALLATION ...
Page 256: ...5 112 469 MOTOR MANAGEMENT RELAY INSTRUCTION MANUAL CHAPTER 5 SETTINGS ...
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