TR-7551-C Transformer Protection Relay WTI for Oil Cooled Transformers

WTIs TR-7551 / TR7552 are designed for safe operation of oil cooled power transformer. It is suitable for control room as well as marshalling box installation and is built for long and trouble-free operation under extreme conditions of services associated with transformer.

Five numbers of user settable set-points can be used to control the cooling fan, to warn the user of high temperature of oil and winding and to shut down the transformer in case of excessive heating (trip). RTD sensor allows the user to monitor the oil temperature, while the C.T. signal is used to calculate and indicate the winding temperature.

TR-7551/52 is programmed to note and store maximum temperature of oil and winding. The maximum temperature reading is stored and saved permanently.

Auto Fan Exerciser feature helps in preventing jamming of fans after no operation for long periods of time. Anticipated Fan control feature turns on the Fan much before the winding temperature reaches the actual fan set point ensuring less thermal shocks and better thermal management of the transformer.

Technical Specifications:

Sensors:

• For oil temperature: RTD Pt-100 (IEC-60751) three wire
• For winding temp simulation: C.T. (C.T. can be of 1 to 5 Amp. secondary current rating & with min. 5 VA capacity)

Programming / Settable parameters:

• C.T. parameterisation
• dt (top oil to winding hot spot temp. gradient) 1 to 50  °C settable
• Thermal Time Constant: 1 to 60 minutes settable

Setpoints:

• 5 for TR-7551: Oil Alarm, Winding Alarm, Oil Trip, Winding Trip and Fan On
• 6 for TR-7552: Oil Alarm, Winding Alarm, Oil Trip, Winding Trip, Fan 1 On and Fan 2 On

Temperature indication range:

• Oil: -40 °C to 150 °C
• Winding: -40 °C to 200 °C (Resolution 1 °C)

Accuracy (Test Conditions: Amb. Temp. 27 °C +/- 10 °C, R.H.: 20-80% non-condensing):

• Oil temperature: +/- 1 °C
• Winding temperature: +/- 2 °C (Excluding C.T. accuracy)
• Maximum recording: in steps of 2 °C (Temperatures above 60 °C are only saved)
• Remote outputs: +/- 1 °C (with respect to local indication)

Mechanical:

• Overall Dimensions: 215 (H) x 265 (W) x 130 (D) mm
• Mounting: Wall mounting by 3 nos. M6 screws
• Weight: 3.0 kg approx. (unpacked)
• Enclosure: Aluminium cast, with polycarbonate viewing window (IP-65)

Electrical

• Five ( 1 C/O) switch contacts rated:
• For resistive load, 5A @ 230VAC & 0.5A @ 125VDC
• For inductive load, 5A @ 230VAC (cosθ = 0.4) & 0.3A @ 125VDC (L/R=7msec)
• Supply Voltage: 90-270VAC/DC (Optionally 20-50VAC/DC), AC 40-400 Hz, Max. 15VA
• Terminals: Screwed Caged suitable for one 2.5mm² wire
• Insulation: 100 Mohm or more when 500 VDC is applied between Earth and terminals. 2KV rms at 50/60 Hz. for 1 min, applied between all terminals shorted together & earth.

Environmental

• Operating conditions: Ambient temperature: -20 °C to 70 °C, Relative Humidity : 95% Max non-condensing
• Storage Temperature: -20 °C to 85 °C
• Vibration: 10-150 Hz, 0.0004" displacement
• Shock: 15g, Half sine, in 3 orthogonal planes