OTI / WTI, 1187, TWM transformer oil and winding thermometers, thermostats
OTI and WTI are dial oil and winding thermometers for power transformers with a manometric system, scales up to +160 °C and a capillary up to 16 m. The range is completed by 1187 thermometers and TWM 7284/7287 thermostats for small and hermetically sealed transformers.
- Types
- OTI (oil), WTI (winding, CT 1/2/5 A); ATI/AWTI (ANSI, in air); 1187-100/150; TWM 7284/7287 thermostats
- Scales
- −50…+150, −20…+140, 0…+150, 0…+160 °C (OTI/WTI); up to 0…+200 °C (1187)
- Microswitches
- up to 6 (OTI/WTI); 2 (1187, TWM)
- Capillary length
- up to 16 m (IEC), up to 10 m (ANSI, TWM), up to 8 m (1187)
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
These indicators monitor two parameters of an oil-filled power transformer. OTI (Oil Temperature Indicator) measures the temperature of the top oil layers, WTI (Winding Temperature Indicator) shows the temperature of the hottest spot of the winding. Their contacts switch on cooling, trigger a warning alarm and trip the transformer in case of unacceptable overheating. On the dial the operator sees the current value and a maximum pointer.
The thermal bulb is immersed in a pocket on the tank cover. A capillary connects it to a manometric system based on a Bourdon tube, which turns the pointer. This arrangement gives stable measurement without recalibration. In the WTI the winding heating is simulated by a heating element fed from a current transformer with a rated current of 1, 2 or 5 A. The devices have a ventilation system against condensate and a protective glass of polycarbonate or glass.
IEC versions work with the bulb in oil. The scales are −50…+150 °C, −20…+140 °C, 0…+150 °C and 0…+160 °C, with up to six microswitches and a capillary up to 16 m. Optionally up to two PT100 sensors and up to four MBO contacts, vibration damping, a pocket and a 4–20 mA output through an external converter are fitted. For the ANSI market there are ATI/AWTI with the bulb in air, scales 0…+120 °C and 0…+180 °C and a capillary up to 10 m. Compact versions are designated OTI-C and WTI-C.
Simpler tasks are covered by type 1187 thermometers with a 100 or 150 mm dial. Their scales range from 0…+120 °C to 0…+200 °C, with two microswitches and a capillary up to 8 m. For hermetically sealed and small transformers the company makes TWM 7284 thermostats without a capillary and TWM 7287 with a capillary up to 10 m, both with two changeover contacts.
The housings are cast from aluminium and painted RAL 7032, with corrosion protection class C4-M. Adjustable flanges fit all transformer designs. The devices are fitted on power and distribution transformers and reactors, new and existing, including in offshore and tropical conditions. For remote monitoring there are digital versions eOTI and eWTI.
Technical specifications
| Types | OTI (oil), WTI (winding, CT 1/2/5 A); ATI/AWTI (ANSI, in air); 1187-100/150; TWM 7284/7287 thermostats |
|---|---|
| Scales | −50…+150, −20…+140, 0…+150, 0…+160 °C (OTI/WTI); up to 0…+200 °C (1187) |
| Microswitches | up to 6 (OTI/WTI); 2 (1187, TWM) |
| Capillary length | up to 16 m (IEC), up to 10 m (ANSI, TWM), up to 8 m (1187) |
| Options | up to 2 PT100, MBO contacts, 4–20 mA output through converter, pocket, vibration damping |
| Principle | Bourdon tube, no recalibration |
Request a price and lead time
OTI / WTI, 1187, TWM transformer oil and winding thermometers, thermostats. We reply within one business day.
Or email sales@usk.ua or call 044 339-50-20.
Customs codes
| UKTZED (Ukraine) | 9025 19 80 00 |
|---|---|
| HS, 6 digits | 9025 19 |
| CN (EU) | 9025 19 80 |
| HTSUS (USA) | 9025 19 80 85 |
| China customs tariff | 9025 19 90 00 |
Codes are for reference: the final code is determined at declaration for the specific model.
Questions and answers
What current transformer feeds the WTI?
The WTI heating element is fed from a current transformer with a rated current of 1, 2 or 5 A.
What is the maximum capillary length?
Up to 16 m in the IEC version, up to 10 m for ANSI and TWM 7287, up to 8 m for 1187 thermometers.
Can a 4–20 mA signal be obtained from a dial thermometer?
Yes, the 4–20 mA output is obtained through an external converter. Optionally up to two PT100 sensors are fitted in the device.
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