ACO Timers

High Voltage Check Time

The period of time that the primary device will wait for its load side terminals to go dead before connecting to preferred supply to the load.

It is possible to use ACO when there are no external CVT’s on the units for load side voltage measurement. For this purpose, ACO allows the user to set the High Voltage Check Time to zero. In this case, the primary device will not check that its load side is dead when performing a restoration from the alternate supply when using Both Ways and Break before Make algorithms.

When High Voltage Check Time is set to a non-zero value, the user is not able to turn ACO On if there are no external CVT’s on the load side and either the Break before Make or Both Ways algorithm is selected. Similarly, the user is not able to change High Voltage Check Time to a non-zero value if there are no external CVT’s on the load side and either Break before Make or Both Ways algorithm is selected. Furthermore, the user is not able to change the algorithm to Break before Make or Both Ways when High Voltage Check Time is set to a non-zero value if there are no external CVT’s on the load side.

WARNING
HAZARD OF ELECTRIC SHOCK OR ARC FLASH It is the responsibility of the user helps to ensure that correct safety procedures are in place to avoid misbehavior of ACO in this particular configuration. Failure to follow these instructions can result in death, serious injury, or equipment damage.

High Voltage Dead Time

The period of time that the primary device will wait after the source voltage drops below the Live Line Threshold setting before deciding that a loss of supply has occurred.

The High Voltage Dead Time value cannot be smaller than the Supply Timeout setting. If Supply Timeout is changed to a value higher than any of the ACO timers, High Voltage Dead Time is changed automatically to the Supply Timeout value rounded up to the next integer.

High Voltage Live Time

The period of time that the primary device will wait after the source voltage rises above or is equal to the Live Line Threshold setting before deciding that a restoration of supply has occurred.

The High Voltage Live Time value cannot be smaller than the Supply Timeout setting. If Supply Timeout is changed to a value higher than any of the two ACO timers, High Voltage Live Time is changed automatically to the Supply Timeout value, rounded up to the next integer.

Operator Warning Time

The period of time that the device will display a countdown alert before performing an ACO Trip or an ACO Close operation.

The Operation Warning Time cannot be greater than the High Voltage Dead/Live Times. Reciprocally, the High Voltage Dead/Live Times cannot be lower than the Operation Warning Time. When a self-healing condition is restored from Waiting/Not Ready to Running, the Operation Warning Time is started immediately after the normal operation is established. This helps to ensure that the changeover will be performed with a delay, even if the High Voltage Dead/Live timers have expired. If the state of any of the two devices changes to Waiting or Not Ready, the Operation Warning Timer stops and resets.