CLP Operation

The Cold Load Multiplier setting is the maximum value for the multiplier applied to the Setting Current for the selected protection elements.

Whenever the Cold Load timer is running, the actual multiplier being applied is known as the Operational Cold Load Multiplier (OCLM).

The Operational Cold Load Multiplier is calculated using the following formula:

Where the Operational Cold Load Time is the time the supply has been lost minus any time it’s been back on.

So when the supply is off, the Operational Cold Load Time is increasing and when the supply is on, the Operational Cold Load Time is decreasing.

This means the OCLM will have a minimum value of 1, and a maximum value equal to the User Set Cold Load Multiplier setting.

Consider a situation where the supply has been off for 60 minutes. If the controller was configured with the default CLP settings, the OCLM would be:

Therefore after the supply had been off for 60 minutes, a multiplier of 1.5 would be applied to the Setting Currents.

So the OCLM would increase linearly from x1 to x2 over a 120 minute period while the supply was off.

When the supply is restored, the OCLM would start at x2 and decrease linearly to x1 over the next 120 minutes if the supply stays on.

While the Cold Load timer is running the controller calculates the OCLM every minute.