OTI WTI Meter in transformer is an essential transformer temperature monitoring instrument used for measuring and displaying the oil temperature and winding temperature of oil-filled power and distribution transformers. The OTI (Oil Temperature Indicator) monitors the top oil temperature, while the WTI (Winding Temperature Indicator) indicates the simulated winding temperature using the thermal image principle. These indicators help operators monitor transformer heating and maintain safe operating conditions.
The OTI WTI Temperature Indicator is designed for continuous temperature indication and can be provided with adjustable alarm, trip and cooling fan control contacts. When the temperature reaches a preset limit, the contacts can be used to activate alarms, cooling equipment or transformer protection circuits. WTI models generally use a CT input and heating element to simulate the effect of winding load current and provide an indication of winding hot-spot temperature.
 
Key Features
Oil Temperature Indicator (OTI) and Winding Temperature Indicator (WTI)
Clear and easy-to-read analog dial display
Accurate transformer oil and winding temperature indication
Adjustable alarm and trip contacts
Cooling fan/pump control contacts available
WTI with CT input and heater arrangement
Robust construction for transformer applications
Different temperature ranges and capillary lengths available
Suitable for new transformer installations and replacement applications
Available with optional remote temperature indication/transmitter arrangements

Applications
OTI WTI Meters are widely used for power transformers, distribution transformers, industrial transformers, substations, power plants and electrical utility systems. They are suitable for transformer manufacturers, electrical contractors, EPC companies and maintenance applications.
OTI & WTI Transformer Temperature Monitoring
The OTI directly senses transformer oil temperature through its sensing bulb and capillary arrangement. The WTI combines oil temperature sensing with a heating element influenced by transformer load current to represent winding temperature. Monitoring both parameters helps detect excessive temperature rise and supports reliable transformer operation.