Date Code 20010719 701 Motor Protection Relay
Settings Calculation
Application Data
4.3
Application Data
It is quicker and easier for you to calculate settings for the SEL-701 Relay if you
collect the following information before you begin:
Specifications of the protected motor including:
Rated full load current.
Service factor.
Locked rotor current.
Maximum locked rotor time with the motor at ambient and/or
operating temperature.
Maximum motor starts per hour, if known.
Minimum time between motor starts, if known.
Additional data regarding the motor application including:
Minimum no load current or power, if known.
Motor accelerating time. This is the normal time required for the
motor to reach full speed.
Maximum time to reach motor full load. This time may be
significantly longer than the motor accelerating time,
particularly in pump motor applications where the motor may
run at full speed for some time before the pump reaches full
head and full load.
Current transformer primary and secondary ratings and connections.
System phase rotation and nominal frequency.
Voltage transformer ratios and connections, if used.
Type and location of resistance temperature devices (RTDs), if used.
Expected fault current magnitudes for motor or cable ground and
three-phase faults.
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