Onload Tap Changer (OLTC) is used with higher capacity transformers where HT side voltage variation is frequent and a nearly constant LT is required. OLTC (On Load Tap Changer) is fitted with the transformer itself. Multiple tapping 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 anticlockwise 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. This movement of contacts thus controls the output LV voltage of the transformer. So rotating of OLTC contacts with spindle or push buttons in this way is a manual process

Function of OLTC AVR:

In case the process of rotating the OLTC contacts and hence controlling the LV side voltage is to be done automatically then an AVR (Automatic Voltage Regulator) is installed with the transformer OLTC.

SE-AVR96: This is a very basic model for automatic voltage regulation of HT Transformer. This is a fully microprocessor based m o d e l w i t h b u i l t i n undervoltage (UV) and over voltage (OV) protection. An aux. relay is provided to generate an alert. Time delay (TD) feature is also enabled in this AVR.

S A G - E 4 4 : T h i s i s a microprocessor based advance model with various features. This model has OV, UV, TD, LDC, AFR, C F R , T P I , P a r a l l e l Operation, SCADA, SMS Alerts, GPS, Sensor Inputs, OL Protection. This model displays data on 128 x 64 pixel mono graphical LCD.

OLTC AVR:

The Automatic Voltage Regulator Relay or AVR Relay 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 sences 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. In "Manual" mode the LV voltage can be controlled through low/high push buttons which are fitted along with OLTC - LCP (Local Control Panel). Up and down movement of OLTC motor is indicated with the glow of LEDs fitted on the AVR and on the OLTC - LCP. This AVR can be used with any type of OLTC as it has to control the movement of motor which is connected with the arm that moves the contacts of the OLTC. The LCP is generally fitted near the OLTC or upon the OLTC box while the RTCC is fitted with the HT panel of the transformer.

Working of OLTC AVR:

OLTC AVR Model:

OLTC AVR Model:

Technical Specifications

The AVR has built in feature for protection against UV/OV from PT. An aux. relay is energized to operate an hooter. The UV and OV state is shown on the LCD. You can also set the AVR to get an SMS on your mobile phone in case of OV/UV.

Over Voltage/Under Voltage Protection:

The affect in change in voltage takes place only after the time delay (TD) has elapsed as set by the user. In other words the relay will send command to the motor only after the time delay has elapsed. This is required to avoid the motor start/stop on frequent voltage fluctuations. This delay time can be set from 5 to 125 seconds.

Time Delay:

This refers to the drop in line voltage from generating end to transformer primary. The LDC helps the AVR to compensate this drop. The feature is added on request on charge-able basis.

Line Drop Compensator (LDC):

If the OLTC/AVR malfuctions because of any reason for certain preset time (say 10 minutes) then the CF relay will get energised and activated. An alarm can be connected with this relay contacts. Once the controls resume the normal functions, the relay gets de-energized putting the alarm off. All this can be seen on the LCD. You can also set the AVR to get an SMS on your mobile phone in case of control failure of the OLTC AVR.

Control Failure Relay (CFR):

In case auxiliary supply to AVR fails (from PT), the AF relay gets activated. You can also set the AVR to get an SMS on your mobile phone in case of auxiliary supply faiure.

Auxiliary Fail Relay (AFR):

Tap Position Indicator (TPI):

The OLTC AVR module has (optional) the provision to operate more than one transformers in parallel. One transformer is taken as the master and the remaining as the followers so that they follow the master's LV voltage set values.

OLTC AVR Parallel Operation:

This feature is used to indicate the tap position. The tap position is displayed on the LCD. You can get tap postion on your mobile phone also (on request).

OLTC AVR model SAG-E44 can be monitored and control through a wireless SCADA application from any where in the world. You can monitor the complete parameters of a transformer like electrical parameters, winding temperature (sensor required), oil temperature (sensor required), oil level (sensor required), buclotz relay status. oil leakage (sensor required).

OLTC AVR On SCADA:

OLTC AVR model SAG-E44 can be provided with a 80 column printer to get instant printouts on the spot. You can select the parameters for which you need the instant printouts.

Printer For Instant Reports:

All the functions and events happening in the OLTS AVR can be received on your mobile phone.

SMS Alerts:

You can see the location of your transformer on google map from any where in the world.

Global Positioning System (GPS):

You can connect 4 X analog sensors (4 - 20 mA OR 0 - 5 volts) to record and monitor the health of the HT transformer. You can connect 4 x digital sensor (pulse/counter) to check the status of transformer buchlotz's relay, transformers breaker etc.,. You can connect winding temperature sensor, oil temperature sensor, oil level sensor at the analog inputs. Data can be monitored on LCD display of the OLTC AVR. If the AVR is GPRS enabled then you can also monitor the live data on SCADA application.

Analog & Digital Sensors:

In case a transformer if getting overloaded, you can get an instant alert on 5 mobile numbers so as to take immediate action. Optional feature can also be provided to start an alarm or switch off the breaker and hence the transformer to save it from over-heating,

In case the AVR is fitted with the energy module then you can monitor the electrical parameters on the LCD display. The parameters can also be monitored on SCADA software or web intefcae live from any where in the world. This feature is used for remote energy managemnet of sub stations and helps in energy savings.

You can generate daily energy consumption reports in excel for review and analysis.

Over Load Protection (OLP):

Electrical Parameters:

Daily Report Generation:

OLTC AVR(OLTC - Automatic Voltage Regulator)

Complete Protection of HT Power Transformers

With

Built-In

And

Finally

Sub Station Automation Features

Remote Monitoring & Control ThroughGSM/GPRS Technology

Its SCADA Enabled

Model: SAG-E44

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Specification SE-AVR96 SAG-E44

Auxiliary Power Supply 110/250 VAC +/-10% 110/250 VAC +/-10%

Frequency 50 Hz 50 Hz

Power Consumption 10 VA 15 VA

PT Supply 110 VAC 110VAC

Time Delay Adjustment 10 - 100 Sec 10 - 100 Sec

Response Time Less Than 5 Sec Less Than 5 Sec

Operating Temperature 55 Deg C 55 Deg C

LCD Display 16 x 2 Line Mono 128 x 64 pixel

Under Voltage Protection a aOver Voltage Protection a aTime Delay Adjustment a aLine Drop Compensator r a

Electrical Parameters r a

Control Failure Relay r aAuxiliary Failure Relay r aTap Position Indicator r aParallel Operation r aSCADA r aPrinter Port (80 Col) r aSMS Alert r aGlobal Positioning System r aAnalog Input (4 Channel) r aDigital Input (4Channel) r aOverload Protection Relay r aCommunication r GPRS/GSM

Dimensions 96 x 96 x 120mm 230 x 110 x 100 mm

Weight 1 Kg (approx.) 4 Kg (approx.)

Designed & Manufactured By

M/s Softbit Technologies Pvt. Ltd.F-35A, Shopping Centre - I,

Mansarover Garden, New Delhi - 110015

INDIA

Phone: +91 11 25438952Mobile: +91 9899445761

Web: http://www.softbitonline.comEmail: info@softbitonline.com

90mm

120mm

96mm

96mm

Back Side

Front Side

OLTC AVR

OLTC AVR

LCD Display

LCD Display

110mm

230mm

100mm

Model: SE-AVR96 Model: SAG-E44

Note: Specifications are subject to change as updation and modifications are a continuous process at our end