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)

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

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