Trips, Alarms, And Blocks; Relay Assignment Practices - GE 469 Instruction Manual

4 SETPOINTS
The 469 has three basic categories of protection elements. They are trips , alarms , and blocks .
• TRIPS: A 469 trip feature may be assigned to any combination of the two Auxiliary relays, R2 and R3, in addition to the
R1 Trip Relay. If a Trip becomes active, the appropriate LED (indicator) on the 469 faceplate will illuminate to show
which of the output relays has operated. In addition to the Trip relay(s), a trip will always operate the Block Start relay.
Trip features are may be programmed as latched or unlatched. Once a relay has been operated by a latched trip, a
reset must be performed to clear the trip when the condition is no longer present. If there is a lockout time, the Block
Start relay will not reset until the lockout time has expired. If an unlatched trip feature becomes active, that trip will
reset itself (and associated output relays) as soon as the condition that caused the trip ceases. Immediately prior to
issuing a trip, the 469 takes a snapshot of motor parameters and stores them as pre-trip values which will allow for
troubleshooting after the trip occurs. The cause of last trip message is updated with the current trip and the 469 display
defaults to that message. All trip features are automatically logged and date and time stamped as they occur. In addi-
tion, all trips are counted and logged as statistics such that any long term trends may be identified.
• ALARMS: A 469 alarm feature may be assigned to operate any combination of three output relays, R4 Alarm, R3 Aux-
iliary, and R2 Auxiliary. When an Alarm becomes active, the appropriate LED (indicator) on the 469 faceplate will illumi-
nate when an output relay(s) has operated. Each alarm feature may be programmed as latched or unlatched. Once a
latched alarm feature becomes active, the reset key must be pressed to reset that alarm. If the condition that has
caused the alarm is still present (e.g. hot RTD) the Alarm relay(s) will not reset until the condition is no longer present.
If 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
RESET
the key is pressed, the Block Start relay will not reset until the 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 enun-
ciate internal 469 faults (these faults include Setpoint 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, R1 Trip, is intended to be used as the main trip relay. Another relay, R4 Alarm, is intended to be used as the
main alarm relay. The two relays that are left, R2 Auxiliary and R3 Auxiliary, are intended for special requirements.
When assigning features to R2 and R3, it is a good idea to decide early on what is required since features that may be
assigned may conflict. For example, if R2 Auxiliary is to be used for upstream trips, it cannot also be used for the control of
a Reduced Voltage Start. Similarly, if R3 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 R1 Trip output relay. All alarms default to the R4 Alarm relay. Only spe-
cial control functions are defaulted to the R2 and R3 Auxiliary relays. It is recommended that these assignments be
reviewed once all the setpoints have been programmed.
GE Multilin
Courtesy of NationalSwitchgear.com
469 Motor Management Relay
4.1 OVERVIEW

4.1.2 TRIPS, ALARMS, AND BLOCKS

4.1.3 RELAY ASSIGNMENT PRACTICES

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