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3.2.5 Up-To / Down-To Count Alarm Relay
Contacts in the LTC wear proportionately to the number of changes they endure. In
most LTC’s the contact surface used in changing Up-To a tap is different than the surface
used in changing Down-To the same tap. As the 1250-LTC is monitoring the movement of
the LTC, it will keep a log of how many times the LTC changes Up-To and Down-To each
tap. A programmable alarm limit (10 to 999,990 counts) can be set, which will assert the
assigned Alarm Relay output and light up the associated LED, if the number of logged
changes Up-To or Down-To any tap reaches the limit. The alarm code “udCLt” will be
displayed momentarily. Please note that the counter limit value is set in THOUSANDS of
tap changes. A date can be entered for reference purposes. (This date is stored in memory
for reference only, it will not increment as time passes. It can be read through the Front Panel
or the serial port.)
Use the OP 70, udCLt, UPDNLMT command to set the Up-To / Down-To Change
Alarm Limit. Use the OP71, udrLY, UPDNRLY command to select which relay (OFF, LO
or HI) asserts when the Up-To / Down-To Change Alarm Limit is reached. When this value
is set to “OFF” this function is disabled.
Use the OP 73, uddIS, DUMP command to display each tap, the Change Up-To
Count, and the Change Down-To Count for that tap. Use the UP and DOWN keys to scroll
through the list of taps. Press the ENTER key to select a tap and display its Change Up-To
Count. Press the ENTER key to display its Change Down-To Count. Press the ENTER key
to return to the list of taps. Press the MENU key to escape back to the programming menu.
The alarm relay will remain asserted until cleared or the counters are reset. Use the
OP 74, udCLr, UPDNCLR command to clear an active alarm without resetting the counters.
Use the OP 75, udrSt, UPDNRST command to clear the alarm and reset all Change Up-To
and Change Down-To counters. The display will read “rESEt”. When using the keyboard
command, press the UP and DOWN keys at the same time to confirm that you want to reset
these counters to zero. Press the MENU key to escape back to the programming menu
without clearing the counters.
3.2.6 Pass-Through-Neutral Alarm Relay
It is important that an LTC pass through the neutral tap(s) on a regular basis. As the
1250-LTC monitors LTC position, it knows when the LTC passes through the neutral tap(s).
The 1250-LTC is intelligent enough to know the difference between stopping at
neutral and reversing direction, and stopping at neutral and continuing on to the tap on the
opposite side of neutral. A timer is started each time a complete “Pass-Through-Neutral”
occurs. It counts the number of days since that event. When the LTC passes through neutral
again, the timer is reset and counting starts over. A programmable limit is set, which will
cause an assigned Alarm Relay output to assert and associated LED to light up, if the number
of days since a “Pass-Through-Neutral” reaches this limit. The alarm code “PtnLt” will be
displayed momentarily.
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