5 Reading and Interpreting MJ-5 Control Panel Data
Siemens Industry, Inc. 41
5.7 Operation Counter Data -
The <COUNTERS> menu
Operation counters record the stepping operations of the
regulator tap changer (see Table 5.7).
Table 5.7 Counter Data Items
1. To reset, use Cancel/Reset key.
2. To change value, use the Change/Save and Scroll keys.
3. Tap position is determined by the “dead reckoning” method
(see below)
4. To view, use Max/Min key.
To retrieve Tap Changer data, use the menu Selection keys
to access the< COUNTERS> menu; then use the ▲ and ▼
keys to sequence through the data.
Dead Reckoning for Siemens Regulators
The control program keeps track of the regulator tap
position by means of a “dead reckoning” procedure,
analogous to navigational dead reckoning. Dead reckoning
must start from a known position. MJ-5 dead-reckoning
begins at Neutral (U12 active, if Tap Resync is ON) or
when an operator inputs a tap position value. Subsequently,
when the microprocessor requests a tap raise/lower (J/K),
and the regulator makes the tap change (asserting
Operations Count signal U10), the control program updates
the tap position value. By this procedure, the MJ-5
maintains continuous tap position information.
If, for some reason, a tap change command is not
confirmed within an appropriate period of time, a Message
condition is raised and dead reckoning is discontinued until
the tap changer once again signals Neutral. Similarly, a
Message condition is activated if an Operation count signal
is received when no tap change command was issued; or if
the U12 PDS lead signals that the tap changer has passed
through neutral at a time when the assumed dead reckoning
position is not neutral.
Note: For application on other manufacturer’s regulators
and LTC apparatus, the MJ-5 implements a similar dead
reckoning procedure for tap tracking. The details of the tap
tracking approach for these applications are included in the
Tap Tracking Application Note.
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