Electronic Oil / Winding Temperature Indicator

1. For Oil Cooled Transformers :

Models : I-005-01 | I-002

Model No. : I-005-01

Electronic Temperature Controller OTC / WTC)

APPLICATIONS

This scheme is used to indicate the Oil and Winding Temperature of the oil-immersed transformers. It will indicate the corresponding oil & winding temperature and controls as per settings. This has two 4-20mA DC Signal outputs for OTI & WTI. THIS SYSTEM IS ELECTRICALLY ISOLATED FROM INPUT POWER SUPPLY.

 

System Architect

The top oil temperature is sensed by PT100 Sensor and measured through the Microcontroller. The Winding temperature is simulated by passing CT secondary Current (from the transformer Line) through a resistance which is connected to the ADC of the Microcontroller. The Microcontroller converts the voltage across the resistance into winding temperature rise in °C over top oil temperature, proportional to square of the CT secondary current. The converted winding temperature rise is added with the top oil temperature and is displayed in °C as winding temperature by the Microcontroller. The Microcontroller also performs the control action as per set values and Differential through the relay provided for this purpose. Also 4-20mA outputs proportional to temperature indicated are provided by additional circuits which are controlled by the Microcontroller. The software provided for this facilitates in selection of Control Settings, Differential for control the relays.

SALIENT FEATURES :

  • EMC compliance.
  • User selectable settings
  • Weather proof case for outdoor services.
  • Remote indication & Data acquisition facility.
  • Zero Offset Adjustment.
  • Power line filter incorporated.
Temperature Sensor : RTD (PT-100 DIN 43760)
No. of sensor inputs : ONE
CT Sec Current Input : 1.0A – 5.0A (User selectable)
Temperature Rise : 1°C – 45°C (User selectable)
No. of set points : 2 independent Output Relay for Alarm and Trip (OTI/WTI)
Range : 0-150°C (Other Ranges on Request)
Resolution : 1°C
Accuracy : ±1°C
Display & WTI indication : 4 Digit Seven Segment LEDs for each OTI
     
Supply Voltage : 90-260V AC/DC
Current Outputs : Two analog DC O/Ps (4-20mA suitable for 250Ω burden).
Current Rating : 5A at 220V AC Res. Load or 1A at 220V DC.
Terminals : Screwed Caged suitable for one 2.5 SQ.mm wire
Insulation : Insulation resistance will be 100 MΩ or more when 500VDC is applied between each terminal and earth.
Equivalent will withstand 2.5KV rms at 50/60 Hz for 1 Minute, applied between all terminals shorted together to earth.
Overall Dimensions : 215(H) x265(W) x 130(D) mm.
Mounting : Wall mounting with Anti-vibration pads and M6 screws.
Weight : Approx. 2.6 Kg without packing box.
Enclosure : IP-55, M.S Sheet Steel Powder Coated enclosure with acrylic window.

Model No. : I-002

ELECTRONIC INSTRUMENT (ROTI / RWTI)

OIL TEMPERATURE INDICATOR

This instrument consists of PT – 100 sensor for sensing the oil temperature. When the oil temperature of transformers rises the resistance of the sensor also increases accordingly. The RTD sensor is connected to a Current Converter Unit (CCU).
The current converter unit converts the oil temperature into 2 sets of 4 – 20 mA DC outputs. An indicator (Analog / Digital) is calibrated for the temperature range connected to the 4 – 20 mA output – 1 from CCU, and second output of 4-20mA can be feed to SCADA / DCS .

WINDING TEMPERATURE INDICATOR

This instrument consists of PT – 100 sensor for sensing the oil temperature and a CT (Current Transformer) is placed inside the current converter unit and is used for simulation of winding temperature. When there is no current flowing through the CT, the winding temperature signal will be zero and result of indication will be proportional to the oil temperature only. When current is passed through the CT the signal proportional to preset temperature rise will be added up to the signal from oil temperature. The output from the CCU will be proportional to the winding temperature.
The current converter unit converts the oil temperature into 2 sets of 4 – 20 mA DC outputs. An indicator (Analog / Digital) is calibrated for the temperature range connected to the 4 – 20 mA output – 1 from CCU, and second output of 4-20mA can be feed to SCADA/DCS


PT 100 sensor assembly
Overall dimension : 6.35mm OD x 150mm Immersion Length
Element : Simplex, 3 – wire system
Nominal resistance as per : DIN IEC 751:1985 (DIN 43760 super seeded)
    B.S.1904: 1984 IS: 2848:1986
Tolerance : Class B
High Voltage test : All terminals to body, 500V AC, 50 HZ for 1 minute.
Insulation resistance test : 100 Meg. Ohms when checked y 500V DC megger.
Current Converter Unit (ROTI & RWTI*) (RWTI is equipped with CT Secondary Input facility)
Signal input : PT 100 RTD, simplex 3 – wire. (From OTI & WTI Sensor)
Signal output - 1 for remote indication :

4 – 20 mA DC corresponding to oil / winding temperature.

Signal output - 2 for SCADA or DAS : 4 – 20 mA DC corresponding to oil / winding temperature
Burden on output signal   600 ohms maximum including loop resistance.
Accuracy   ±1 % of FSD
Degree of protection of enclosure   IP 40
Warm up time after switching ON   30 minutes (minimum)
High Voltage test   All terminals from 8 - 11 to body, 2kV AC, 50 HZ for 1 minute.
Insulation resistance test   20 Meg. Ohms when checked y 500V DC megger
Digital Remote indicator
Type : 3 1/2 digits, 7 segment LED display
Auxiliary supply : 90 – 260V AC/DC
Suitable signal input : 4 – 20mA DC
Temperature indicator range : 0 – 150 °C
Resolution : 0.1 °C
Accuracy of the system : ±1 % of FSD
Warm up time after switching ON : 15 minutes (minimum)
Degree of protection of enclosure : IP40
High Voltage test : Terminals 1 & 2 to earth, 500V AC, 50 HZ for 1 minute.
    Terminals 3 & 4 to earth, 2kV AC, 50 HZ for 1 minute
Insulation resistance test : 20 Meg. Ohms when checked y 500V DC megger.

2. Dry Type Transformers

Model : I-001-01

Model No. : I-001-01

Electronic Temperature Controller (WTC)

APPLICATIONS

This instrument is used for monitoring the winding temperature of the dry type transformer. It will display the winding temperatures and take necessary control action as per the configuration and differential values set by the user. The protection system also records the maximum temperature and will display the same along with corresponding channel number when ever corresponding push button pressed.

 

System Architect

Transformer protection system incorporates RTD’s which senses the temperature of the winding and displays in degree Celsius (0 C). As the system is controlled by the microcontroller and its software, the operator can set the operating value differential values along with the delay values to enable the system to take necessary control action as and when the measured values crosses the set point for FAN, ALARM & TRIP as per the program.

The system stores maximum temperature of winding in its memory with corresponding channel number and it displays when ever operator called it. Depending upon selection, the temperature value of selected channel or maximum of all winding temperature is converted to 4 – 20 mA DC and transmitted it to data acquisition system or recorder or remote indicator.
User can change / select any parameter as per the menu easily as the system is controlled by the microprocessor and its embedded software, all the push buttons for setting now been arranged ergonomically and instruction are user friendly.

SALIENT FEATURES :

  • Power line filter is incorporated in the input of the power supply to protect the equipment from sudden voltage surges and also to avoid erratic operation in the presence of RF interference.
  • High scanning speed (All 4 channels are scanned in less than 1second).
  • Weather proof case – IP55 enclosure is provided for the instrument to make it suitable for outdoor services.
  • Remote indication and Data acquisition facility.
Temperature sensor : RTD (PT-100 DIN 43760)
No. of sensor inputs : Four / Eight / Twelve
No. of set points : Three (Fan, Alarm and Trip)
Temperature range : 0 - 300° C
Resolution : 0.1° C
Accuracy : ±1°C
Display speed : User settable (0 – 99 seconds)
Display : Five seven segment LEDs One for channel No. and Rest Four for displaying temperature)
Supply Voltage : 90 – 260V AC/DC
Outputs : 1No. Analog output DC 4 – 20mA
Communication : RS-485 MODBUS RTU Protocol (optional)
Relay contact rating : 5A@220VAC / 5A@30VDC
Terminals : suitable for 2.5 sq mm wire
Insulation : Insulation resistance 100Mohms min @ 500V.
Equipment will withstand 2kV rms at 50 / 60 Hz for one minute, applied between all terminals shorted together and earth.
Power consumption : 5 watts
Overall dimension : 215(H) x 265(W) x 130(D) mm
Mounting : Wall mounting with anti vibration pads and M6 screws
Weight : 2Kg Approx
Enclosure : IP-55, M.S Sheet Steel Powder Coated enclosure with acrylic window