Schweitzer Engineering Laboratories SEL-701, Instruction Manual

Page: 49 / 468

Date Code 20010719
701 Motor Protection Relay
Installation
Relay Connections
2.13
Contact Outputs
The SEL-701 Relay is equipped with five contact outputs. Each one provides a
normally opened and a normally closed contact. The contacts are rated to switch 8 A
resistive at 250 Vac. For dc operation, the contacts are rated for tripping duty,
according to IEEE standards.
The contact positions indicated in Figure 2.11 on page 2.14 and on the relay
chassis are the positions the contacts are in when the relay is deenergized. The relay
self-test ALARM contact always operates in a fail-safe mode; you can use relay
settings to program the remaining outputs for fail-safe operation. When you set an
output to operate in fail-safe mode, the relay holds the contact in an energized position
continuously, then deenergizes the contact to trip. The contact is also deenergized if the
relay input power is removed. The connections shown in
Figure 2.11 on page 2.14 are
suitable for use with a motor contactor when trip fail-safe operation is desired.
When you set an output to operate in nonfail-safe mode, the relay energizes the
contact to trip. The contacts do not change position when relay input power is removed.
NOTE:
When you select trip fail-safe operation, the relay will
automatically trip the motor when input power is removed
from the relay or if the relay fails. This is desirable if the
protected motor is more valuable than the process the motor
supports. If the process is more valuable than the motor,
disable trip fail-safe operation and make appropriate wiring
modifications. See
Output Contact Fail-Safe, Trip Duration, &
Starting Lockout Settings on page 4.45 in Section 4: Settings
Calculation
for additional information on fail-safe settings.