MEC 2 MICROPROCESSOR ENGINE/GENERATOR CONTROLLER
PM056 Rev 6 05/10/15 Thomson Technology
19
4.2. INTERNAL FAULT CIRCUITS
The MEC 2 Engine Controller provides four internally activated fault circuits as described
below. All internal fault circuits are provided as standard with every MEC 2 controller.
4.2.1. OVER CRANK
The over crank fault circuit is initiated when the engine fails to start after the
selected crank time or number of crank cycles. The over crank fault circuit is
internally programmed as a latching shutdown fault and is not user
programmable. Refer to the programming instructions for further information.
4.2.2. OVER SPEED
The over speed fault circuit is initiated when the engine’s speed has increased
above the over speed setpoint. The over speed fault circuit is internally
programmed as a latching shutdown fault. The over speed shutdown fault circuit
is programmable for the percentage of nominal engine speed (i.e. over speed
setpoint) and for the transient time delay period. The programming prompts for
over speed are located in the main menu programming loop. Refer to the
programming instructions for further information.
4.2.3. LOSS OF SPEED
The loss of speed fault circuit is initiated when the engine’s speed sensing circuit
does not detect a speed signal for a period more than 2 seconds following a run
signal. The loss of speed fault may be user programmed as a latching shutdown
fault or alarm only. The programming prompts for loss of speed are located in
the main menu programming loop. Refer to the programming instructions for
further information.
4.2.4. SWITCH NOT IN AUTO
The “Switch Not In Auto” fault circuit is initiated when the controller’s operating
mode switch is changed from the auto position to any other position via the front
mounted keypad. This fault is internally programmed as a non latching alarm. In
the main programming loop, this alarm may be user programmed to initiate the
common fail output relay.
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