Tec System T-538 Protection Relay

The Tec System T-538 Protection Relay is a microprocessor-based temperature monitoring and protection device that continuously monitors up to eight Pt100 RTD inputs (3-wire) and automatically drives cooling fans, alarm outputs, and trip circuits when preset thresholds are exceeded, guarding dry-type transformers, generators, motors, and other industrial electrical equipment. It operates on 24–240 VAC/VDC with 50/60 Hz and features a dual digital LED temperature display. The unit offers two programmable alarm relays (ALARM and TRIP), one or two programmable fan control relays (model dependent), and a fault relay for sensor/system fault signaling, with a 10 A at 250 VAC ( resistive) contact rating. Temperature monitoring ranges from 0°C to 240°C and the front panel is IP65 rated for protection; mounting is panel-mount in a 92 × 92 mm DIN 43700 cutout. Common applications include electrical substations, industrial plants, power generation facilities, and transformer protection systems, where reliable thermal monitoring is essential. This relay is used for OEM replacement, preventive maintenance, retrofit, and system upgrades, and is commonly referenced as part of the NT538 family (NT538, NT538 AD, NT538 ETH); it is manufactured by Tec System (TECSYSTEM S.r.l.) with the part number T-538.