Modex Automation – TR900 – Three-Attempt Start Timer Relay, 24 V DC, 8-Pin Plug

The Modex TR900 is a compact 8-pin timer relay designed to control engine or generator starting systems. It performs up to three timed start attempts, energizing separate relay contacts for each phase. If the engine fails to start after the third pulse, the unit locks out via RL2. Designed for 24 V DC systems, the TR900 is ideal for automotive, marine, and industrial generator control panels.

Key Features:

• Model: TR900

• Function: Three-attempt start timer

• Supply Voltage: 24 V DC

• Base Type: 8-pin round plug-in (standard relay socket)

• Relay Logic:

  • Pin 1: Supply –ve DC

  • Pin 8: Supply +24 V DC

  • Pin 3 & 4: RL2 (normally open & common), energized after 3rd failed pulse

  • Pin 5 & 6: RL1 (normally open & common), energized during pulses

• Pins 2 & 7: Not used

• Manufacturer: Modex Automation, Hayling Island, England

• Mounting: DIN rail or panel with compatible 8-pin socket

• Application Type: Engine/generator start controller

• Indications: Printed pinout and function directly on housing

• Relay Ratings: (typical) 5 A @ 24 V DC (confirm with datasheet for specifics)