Dry Type Transformer Temperature Control: Pt100 Sensors, Fans, and Tripping

A dry type transformer thermal controller monitors winding heating through Pt100 platinum sensors. When temperatures cross specific operational limits, the system triggers cooling fans, activates warning alarms, or sends trip signals to isolate circuit breakers from overload damage.

Pt100 Temperature Sensing Mechanics

Embedded Pt100 platinum sensors detect internal winding heating by changing electrical resistance proportionally with temperature rises. Installing these sensors directly into low-voltage windings allows accurate measurement across industrial applications, including smaller units like a 15kva dry type transformer.

Resistance Temperature Detectors utilize a three-wire bridge configuration to compensate for lead wire resistance. Continuous analog feedback feeds directly into digital microprocessors, enabling precise real-time thermal monitoring while preventing local hot spots from degrading internal insulation materials.

Operational Logic for Forced Air Cooling

1. Fan Start Activation: Rising winding temperatures reach predefined setpoints, typically around 100°C for Class F insulation. Controller outputs send signals to energize forced air cooling blowers, preventing thermal overload in systems like a 150kva dry type transformer.

2. Fan Stop Deactivation: Cooling fans run continuously until internal heat drops below set threshold hysteresis band, usually 80°C. Automatic deactivation prevents unnecessary fan wear while maintaining steady operating temperatures under changing electric loads.

Relay Output and System Communication Integration

Modern controllers feature dedicated relay outputs linked directly to programmable logic controllers. Relay channels transmit instantaneous fault alarms and sensor failure warnings, protecting connected electrical apparatus including any isolated dry type transformer installed within remote substation enclosures.

Alarm and Over-Temperature Tripping Sequence

Over-temperature protective sequences execute through two distinct logic stages. Early warning alarms trigger near 130°C, notifying supervisory networks via Modbus RTU or potential-free dry contacts before thermal stress creates severe mechanical stress within core assemblies.

If temperatures surge past 150°C, secondary protection relay circuits energize main breaker trip coils immediately. This trip function insulates equipment like a 225 kva dry type transformer from irreversible coil breakdown during sustained system faults.

Specialized custom configurations apply modified setpoints to accommodate specific phase requirements or compact enclosures. Integrating protective monitoring ensures continuous operation for specialized power distribution setups, such as a single phase dry type transformer operating in restricted technical spaces.