45
Use the OP 85, PtnLt, PTNLMT command to set the “Pass-Through-Neutral” Alarm
Limit (0.1 to 365.0 days with 0.1 day resolution). Use the OP86, PtrLY, PTNRLY
command to select which relay (OFF, LO or HI) asserts when the “Pass-Through-Neutral”
Alarm Limit is reached. When this value is set to “OFF” this function is disabled. Use the
OP 87, PtdIS, DUMP command to display the number of days since the last “Pass-Through-
Neutral” occurred. The relay will remain asserted until the alarm is cleared. Use the OP 88,
PtnCL, PTNCLR command to reset the “Pass-Through-Neutral” counter. This command
will also clear an active “Pass-Through-Neutral” alarm.
3.2.7 One-Direction Change Alarm Relay
Typically, an LTC will move a few taps up or down, then reverse direction and move
a few taps, and reverse direction again. In most cases, it is unusual that the LTC will move
very many taps consecutively in one direction. If this occurs, it may indicate some sort of
failure in the position control system. The consequences of an out-of-control LTC could be
serious – especially in the case of parallel transformers.
As the 1250-LTC monitors LTC position, it can be programmed to assert an alarm
relay if it sees the LTC move too many taps consecutively in one direction, up or down. A
programmable alarm limit (2 to 50) can be set, which will cause an assigned Alarm Relay
output to assert and associated LED to light up, if the number of consecutive tap changes in
one direction reaches this limit. The alarm code “1dCLt” will be displayed momentarily.
Use the OP 90, 1dCLt, 1DTCLMT command to set the “One Direction Change”
Alarm Limit. Use the OP 91, 1drLY, 1DTCRLY command to select which relay (OFF, LO
or HI) asserts the FIRST TIME the “One Direction Change” Alarm Limit is reached. When
this value is set to “OFF” this function is disabled. Use the OP 93, 1ddIS, 1DTCDIS
command to display the number of days since the “One Direction Change” alarm was
asserted. The relay will remain asserted until the alarm is cleared. To clear the alarm, use the
OP 93, 1dACL, 1DACLR command.
3.2.8 FA 25 and FA 27 Alarm Relays
The 1250-LTC continuously performs sophisticated analysis of the input signal. If it
detects a loss of signal, it will display an error code “FA 25”. If it detects that the input signal
has been unstable (caused by noise or continuous LTC movement) for more than 5 seconds, it
will display an error code “FA 27”. These alarms can be programmed to “automatically
reset” when the condition is no longer valid. It can be programmed to assert an alarm relay
when each of these errors occurs. These are Transient relay actions.
Use the OP 53, Aut25, AUTO25 command to enable or disable the automatic reset
for the FA 25 error alarm. Use the OP 54, 25rLY, FA25RLY command to select which relay
(OFF, LO or HI) asserts while the FA 25 error is being displayed. Use the OP 60, Aut27,
AUTO27 command to enable or disable the automatic reset for the FA 27 error alarm. Use
the OP 61, 27rLY, FA27RLY command to select which relay (OFF, LO or HI) asserts while
the FA 27 error is being displayed.
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