GE DS3800TIMC

Key Parameters

• Timers: 8 independent 32-bit timers (software-configurable)

• Timer Resolution: 1ms, 10ms, 100ms, or 1s (jumper-selectable per timer)

• Counters: 4 independent 32-bit up/down counters

• Counter Input: Accepts pulse signals up to 50kHz (TTL or 24V DC)

• Outputs: 8 dedicated timer/counter output channels (open-collector, 24V DC, 0.5A)

• Accuracy: ±0.01% over full temperature range

• Diagnostics: LED status per timer/counter, watchdog timer, battery-backed counter retention

• Battery Backup: Lithium 3.6V for counter value retention during power loss

• Temp Range: –30°C to +70°C

• Power Supply: +5V (logic), +24V (outputs) from backplane

• Physical: 6U VME single-slot board

Advantages

• Hardware-based timing – the DS3800TIMC provides sub-millisecond accuracy that cannot be achieved by software timers running on the main processor.

• Independent operation – timers and counters continue functioning even if the main processor communication is disrupted, ensuring critical time-based trips remain active.

• Flexible configuration – each timer can be configured for one-shot, retriggerable, or free-running modes, accommodating various turbine logic requirements.

• Counter retention – battery backup preserves run-time counters (e.g., turbine operating hours, starts count) through power cycles.

• High-speed counting – accepts up to 50kHz pulse inputs for speed or flow measurement applications.

• Drop-in compatible – works with all Mark IV backplanes and processor configurations.

Applications

• Turbine purge timing – ensures proper purge duration before ignition (critical for safety).

• Ignition and warm-up delays – controls flame stabilisation time and warm-up ramp rates.

• Run-time accumulation – tracks turbine operating hours, starts, and trips for maintenance scheduling.

• Speed measurement – counts pulses from magnetic pickups for speed monitoring (used with overspeed protection logic).

• Flow totalization – accumulates pulse outputs from turbine flow meters for fuel consumption tracking.

• Cycle timing – controls periodic functions such as valve stroke tests and bearing oil flushing intervals.

vs Competitors & Related Variants

Selection Tips

• Timer mode selection – verify the required mode (one-shot, retriggerable, or free-running) for each timing function before installing the General Electric DS3800TIMC.

• Resolution setting – select the appropriate resolution (1ms, 10ms, 100ms, or 1s) via jumpers for each timer; higher resolution consumes more backplane bandwidth.

• Counter input type – confirm the pulse source matches the DS3800TIMC input requirements (TTL 5V or 24V DC); use external signal conditioners if necessary.

• Battery check – verify the 3.6V lithium battery voltage (should be >3.0V) before commissioning; replace every 5 years.

• Spare strategy – keep one DS3800TIMC per 8–10 installed units; timing boards are critical for startup sequences and should be available for immediate replacement.

Critical Precautions

• Battery replacement – power down the rack before changing the battery on the DS3800TIMC; observe correct polarity. If the battery is disconnected while powered, counter values may be corrupted.

• Input over-voltage – never apply voltage above 30V to the DS3800TIMC counter inputs; this can damage the input optocouplers.

• Output short – do not short the open-collector outputs to ground or positive supply; this can damage the output transistors of the General Electric DS3800TIMC.

• Timer accuracy – for critical timing functions (e.g., overspeed trip delays), verify accuracy at the operating temperature using an external oscilloscope; temperature drift is minimal but should be confirmed during commissioning.

• Jumper documentation – record the jumper settings for each DS3800TIMC in your facility; lost jumper configurations can be difficult to reconstruct.

• Hot-swap – never insert or remove the DS3800TIMC while the rack is powered; this can cause timer drift or backplane damage.

• Grounding – use shielded cables for pulse inputs to the DS3800TIMC; grounding the shield only at the board end prevents noise pickup.

• Humidity – store spare DS3800TIMC boards in anti-static bags in a dry environment; high humidity can affect the high-impedance input circuitry.