27-03-2012, 11:47 AM
REMOTE TAP CHANGER CONTROL PANEL
5thRTCCmain.pdf (Size: 3.35 MB / Downloads: 307)
RTCC is “Remote Tap Changer Control “which is a Programmable device to
control the output of the transformer through OLTC unit fitted in the transformer
through control cables. The desired voltage will be achieved accordingly by
controlling the OLTC with respect to the tap position through RTCC system. The
output voltage of the transformer is been maintained through an inbuilt AVR
(Automatic Voltage Regulator), which continuously verifies the output power with
the set / programmed reference voltage, which triggers the OLTC accordingly.
Hence, by above said phenomena, the consistency of the transformer output is
been maintained.
ON LOAD TAP CHANGER (OLTC)
On load Tap Changer (OLTC) is used with higher capacity transformers where
HT side voltage variation is frequent and a nearly constant LT is required. OLTC
is fitted with the transformer itself. Multiple tapings from HV windings are
brought to the OLTC chamber and connected to fixed contacts. Moving contacts
rotates with the help of rotating mechanism having a spindle. This spindle can be
rotated manually as well as electrically with a motor. Motor is connected in such a
way that it can rotate in both the directions so as to rotate the OLTC contacts in
clockwise and anti clock-wise direction. Two push buttons are fitted on the LCP
(local control panel) to rotate the motor and hence the OLTC contacts in clockwise
and anti-clockwise direction.
CHARACTERISTICS:-
Wide Range
Voltage Class 11kv, 22kv, 33kv, 66kv and 132 neutral end
Current Rating up to 500 Amps
Single phase off circuit Tapchanger upto 2000 Amps
Type tested as per IS and IEC standards
Tapchangers for Furnace application
6, 9, 10,17, 21, positions
Suitable for bidirectional power flow
Supplied with Remote Tapchanger Control Cubicle
Compatible for SCADA and computer controls
The Automatic Voltage Regulator Relay -
AVR-MA9, is a totally
microprocessor based relay that controls the arm movement with the help of high
torque motor (OLTC and motor are not parts of the AVR supply). It also indicates
the line voltage, line current, load on the transformer, apparent and reactive
powers, system frequency and power factor. The AVR can be set to "Auto" or
"Manual" mode. In "Auto" mode the AVR controls and maintains the transformer
LV voltage as per the pre set value automatically. It senses the variations in LV
voltage for a pre-set time delay and brings the voltage to normal value by
changing the tap position of OLTC with the help of high torque motor.
CONTROLS
1. Power ON:-
This is a toggle switch which when ON supplies Auxiliary voltage to the
instrument.
2. R-Set:-
This is a variable control varying from 0.5V to 5.0V below NVA setting. This
control sets the lower limit of the PT Voltage below which if the voltage reduces,
then corrective action will be taken by the instrument. The setting is to be read on
display.
3. ‘NOM’ Set:-
This is a variable control to set the nominal value of PT voltage varying between
±10% of 110V.This setting becomes the reference level around which is to be read
on the display.
4. ‘L’ Set:-
This is a variable control varying from 0.5V to 5.0V above NVA setting. This
control sets the upper limit of the PT Voltage below which if the voltage reduces,
then corrective action will be taken by the instrument. The setting is to be read on
display.
5. Time Delay:-
Corrective action takes place only after the time delay as set by the control has
elapsed and the PT Voltage continues to remain outside the set Lower or raise
limits (but does not fall below the UV/OV limit)