Allen-Bradley 825-P User Manual

Rockwell Automation Publication 825-UM004D-EN-P - November 2012 101
Configuring Protection & Logic Functions Chapter 6
The relay automatically locks out the trip relay by asserting the trip signal under
any of the following start-inhibiting conditions:
• Restart (Anti-backspin) Block
The restart block timer has not expired since the motor trip occurred. The
trip c
ondition is maintained until the timer expires.
• Min
imum Time Between Starts Lockout
A new st
art is not permitted until after the minimum time between starts
has p
assed. The trip condition is maintained until a start is permitted.
• Starts-Per-Hour Limit Lockout
If
the starts-per-hour limit has been met, a new start is not permitted until
60 min
utes after the oldest start. The trip condition is maintained until a
start is permitted.
• TC
U Start Inhibit
The
motor thermal element % Thermal Capacity value is too high to
per
mit a normal motor start without tripping. The trip condition is
maintained until the % Thermal Capacity decreases to a level where a start
can safely take place.
If any of the above protection functions is not enabled by the relay settings, that
funct
ion does not affect trip unlatch.
Also note that the relay automatically asserts the trip signal if the motor stops and
a lockout condition is true. The trip signal is maintained until all the enabled
motor lockout conditions are satisfied.
Trips initiated by the serial port command or by network operation are
maintained for at least 0.5 second.
Start & Emergency Restart Logic
If the Trip output contact is not asserted, the relay asserts the START Relay Word
bit in response to any of the following conditions:
• t
he Emergency Restart Relay Word bit asserts.
• you execute the STR
serial port command or a DeviceNet Start Motor
control command.
The START Relay Word bit remains asserted for 0.5 seconds, unless the relay
tri
ps. If the relay trips before the 0.5 second timer expires, the relay resets the
timer, clearing the START Relay Word bit.
In an emergency, it could be necessary to quickly start the motor even though
a protection lockout condition exists and is holding the Trip output contact
asserted. The lockout might be a result of the thermal element or another
protection function. You can override all of the lockout conditions using the
Emergency Restart function.

Allen-Bradley 825-P Specifications

General

Brand	Allen-Bradley
Model	825-P
Category	Power distribution unit
Language	English