TR42 — temperature monitoring relay for dry-type and cast resin MV transformers (ANSI 49) with PT100 sensors, PTbox and control cabinet
TR42 is a microprocessor temperature monitoring relay (ANSI 49) for three-phase dry-type and cast resin MV transformers with four PT100 inputs. The relay controls two fan stages, gives two alarm setpoints and a trip command. The versions are made with RS-485 Modbus RTU, with a 4–20 mA output or with Ethernet.
- Inputs
- 4 PT100 sensors (3-wire), line resistance up to 500 ohm
- Range
- −10…+240 °C, accuracy ±1 % of scale ± 1 digit
- Setpoints
- L1, L2, FAN1, FAN2: 0…220 °C
- Outputs
- FAN 16 A 240 V AC (7 A continuous); L1, L2 changeover 5 A 250 V AC; FAULT 5 A
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
The TR42 monitors the winding temperature of three-phase cast resin dry-type transformers and works with machines of any voltage class and rating. A microprocessor compares sensor readings with the set program in real time. Based on the result, the relay switches the cooling fans on or off, gives a warning signal and generates a trip command for the circuit breaker. Two-stage cooling helps in hot weather or under current overload, when the transformer must be kept under load without thermal overheating of the insulation.
The measuring part has four inputs for three-wire platinum PT100 resistance temperature detectors with a line resistance of up to 500 ohm. The measuring range is −10…+240 °C, accuracy is ±1 % of scale ±1 digit. Three channels are usually assigned to the winding phases and the fourth to the core, and the number of active channels is selected as 1, 3 or 4. The relay polls the sensors automatically, detects an open circuit and a short circuit in the circuit of each of them and stores peak temperatures.
Four independent programmable outputs have setpoints of 0…220 °C. Two of them, L1 and L2, work as alarm levels, and the other two, FAN1 and FAN2, control two fan stages. For the fans there is an always-on mode and a weekly automatic start, so that the bearings do not seize during long idle periods. The FAN contacts switch 16 A 240 V AC (7 A continuous), the alarm contacts 5 A 250 V AC, and a separate FAULT relay reports a malfunction. The TR42CM version has an isolated RS-485 Modbus RTU port, the TR42AD adds a programmable 4–20 mA output by selected sensor, scanning or maximum value, and the TR42E connects to Ethernet. The supply is 85–264 V AC (115–300 V DC) or 24 V DC.
The device is panel-mounted, and its 96 × 96 × 114 mm case is made of self-extinguishing ABS. The degree of protection on the front is IP54, the terminals are pluggable for 4 mm² wire, the test voltage is 2 kV, and the design complies with VDE, UL and CEI standards. In terms of connection, the TR42 is fully compatible with the earlier TR-42S1 and TR-42C1. The manufacturer supplies the relay with PT100 sensors in silicone insulation with a Teflon shield and a 2 m AISI 316 stainless steel sleeve, a PTbox junction box (ABS, IP65, 158 × 118 × 76 mm) for three class B sensors, and a 300 × 300 × 150 mm wall-mounted cabinet. The cabinet contains the TR42 and a selector switch, and manual or automatic fan control, a buzzer and a contactor for high-power fans can be added on request.
Technical specifications
| Inputs | 4 PT100 sensors (3-wire), line resistance up to 500 ohm |
|---|---|
| Range | −10…+240 °C, accuracy ±1 % of scale ± 1 digit |
| Setpoints | L1, L2, FAN1, FAN2: 0…220 °C |
| Outputs | FAN 16 A 240 V AC (7 A continuous); L1, L2 changeover 5 A 250 V AC; FAULT 5 A |
| Supply | 85–264 V AC (115–300 V DC) or 24 V DC, consumption 4 VA |
| Communication | isolated RS-485 Modbus RTU (1500 V DC); 4–20 mA (TR42AD); Ethernet (TR42E) |
| Case | 96×96×114 mm, panel cutout 91×91 mm, IP54 front, ABS, 500 g |
| Versions | TR42CMW5/CMB5, TR42ADW5/ADB5, TR42EW5/EB5 |
| Accessories | PT100 sensors (2 m, AISI 316), PTbox (IP65, 3×PT100), cabinet 300×300×150 mm |
Request a price and lead time
TR42 — temperature monitoring relay for dry-type and cast resin MV transformers (ANSI 49) with PT100 sensors, PTbox and control cabinet. We reply within one business day.
Or email sales@usk.ua or call 044 339-50-20.
Customs codes
| UKTZED (Ukraine) | 8536 49 00 00 |
|---|---|
| HS, 6 digits | 8536 49 |
| CN (EU) | 8536 49 00 |
| HTSUS (USA) | 8536 49 00 85 |
| China customs tariff | 8536 49 00 00 |
Codes are for reference: the final code is determined at declaration for the specific model.
Questions and answers
Which transformers is the TR42 suitable for?
For three-phase dry-type and cast resin transformers of any voltage class and rating. Three PT100 inputs monitor the winding phases, and the fourth can be used for the core.
What load can the fan outputs withstand?
The FAN contacts are rated 16 A 240 V AC, continuous current 7 A. For higher-power fans a contactor is fitted in the wall-mounted cabinet.
What communication interfaces does the TR42 have?
The TR42CM has RS-485 Modbus RTU with 1500 V DC isolation, the TR42AD additionally a 4–20 mA output, and the TR42E an Ethernet port.
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