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CHAPTER 5: SETTINGS
5.1.3
Relay Assignment Practices
469 MOTOR MANAGEMENT RELAY – INSTRUCTION MANUAL
on the other hand, an unlatched alarm feature becomes active, that alarm will reset
itself (and associated output relay(s)) as soon as the condition that caused the alarm
ceases. As soon as an alarm occurs, the alarms messages are updated to reflect the
alarm and the 469 display defaults to that message. Since it may not be desirable to
log all alarms as events, each alarm feature may be programmed to log as an event or
not. If an alarm is programmed to log as an event, when it becomes active, it is
automatically logged as a date and time stamped event.
•
BLOCK START: A 469 Block Start prevents or inhibits the start of the motor based on
some logic or algorithm. The Block Start feature is always assigned to the Block Start
relay. In addition to the Trip relay(s), a trip always operates the Block Start relay. If the
condition that has caused the trip is still present (e.g. hot RTD), or there is a lockout
time when the
RESET
condition is no longer present or the lockout time has expired. Blocking features are
always unlatched and reset immediately when conditions that caused the block
cease. In addition to becoming active in conjunction with trips, a block may become
active once the motor stops. There are several features that operate as such: Starts/
Hour, Time Between Starts, Start Inhibit, Restart Block, and 469 Not Programmed.
Block messages are updated to reflect the block when it becomes active (complete
with lockout time if required) and the screen defaults to that message. Blocks are
normally not logged as events. If however, a motor start or start attempt is detected
when a block is active, it is automatically logged as a date and time stamped event.
This scenario might occur if someone shorts across the block terminals and overrides
the 469 protection to start the motor.
There are six output relays. Five of the relays are always non-failsafe, the other (Service) is
failsafe and dedicated to enunciate internal 469 faults (these faults include settings
Corruption, failed hardware components, loss of control power, etc.). One of the output
relays is dedicated as the Block Start relay; it is dedicated to features that are intended to
block motor starting. The four remaining relays may be programmed for different types of
features depending on what is required. One of the relays, 1 TRIP, is intended to be used as
the main trip relay. Another relay, 4 ALARM, is intended to be used as the main alarm relay.
The two relays that are left, 2 AUXILIARY and 3 AUXILIARY, are intended for special
requirements.
When assigning features to Auxiliary Relays 2 and 3, it is a good idea to decide early on
what is required since features that may be assigned may conflict. For example, if
2 AUXILIARY is to be used for upstream trips, it cannot also be used for the control of a
Reduced Voltage Start. Similarly, if 3 AUXILIARY is to be dedicated as a relay to echo all
alarm conditions to a PLC, it cannot also be used strictly to enunciate a specific alarm such
as Undercurrent.
In order to ensure that conflicts in relay assignment do not occur, several precautions have
been taken. All trips with the exception of the Short Circuit Backup Trip default to the 1 TRIP
output relay. All alarms default to the 4 ALARM relay. Only special control functions are
defaulted to Auxiliary Relays 2 and 3. It is recommended that these assignments be
reviewed once all the settings have been programmed.
key is pressed, the Block Start relay will not reset until the
5–7
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