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7
Other Features
7.1
Instrumentation and Metering
The MicroTAPP gives indications, shown by reference to the general layout in appendix A as follows: -
7.1.1 System ID
The relay has provision for input of a control system ID, e.g. "Transformer 1".
7.1.2 Control Switches
The relay status is indicated on the LCD display. The controls are integral within the voltage control relay, the
display shows the control switch selection, see Figure 16.
7.1.3 Relay Healthy
An LED shows that the relay is operating correctly or has malfunctioned.
7.1.4 Voltmeter
Digital presentation of the power system voltage is shown on the LCD.
7.1.5 Voltage Trace
A voltage level trace is shown on the LCD.
This can be configured for a window of 15 minutes or 1 hour.
7.1.6 Tap Position Indicator (TPI)
Digital presentation of tap position is shown on the LCD.
Some tap changers have special positions which operate to re-arrange the winding configuration but do not alter
the voltage. When at these positions a single tap change control will result in more than one tap change
operation. The positions may also be indicated as the same position and labelled with suffix letters, i.e. 8A, 8B,
8C.
A system that allows for presentation of the tap position as indicated on the tap change mechanism is integrated
into the TPI set-up menu, accessed by use of a 'tap customisation sub-menu'. If a tap position is maintained as
the same position through the 'transfer' cycle, the positions can be re-numbered as the same position, for
example 7, 8, 8, 8, 9. To indicate that these tap positions are special, they should also be marked as 'T' to
indicate a 'Transfer' position, i.e. 7, 8T, 8, 8T, 9. This prevents a Runaway condition being detected.
The use of the sub-menu is best understood from the following examples.
A tap changer with top tap of 15 but with tap through positions labelled 8A, 8B and 8C.
1 2 3 4 5 6 7 8A 8B 8C 9 10 11 12 13 14 15
The total number of positions are 17 and entered in the in the settings/tap change/ no. of taps as 17. The tap
customisation sub-menu is used to change the tap positions as follows:-
1
2
3
4
A tap changer with a tapping range from -5 through 0 to +11 the total number of positions is 17 and entered in the
settings/tap change/no. of taps as 17.
©2013 Siemens Protection Devices Limited
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8T 8
7SG15 MicroTAPP Description of Operation
8T 9
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Chapter 1 Page 21 of 38
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