• Shots failed
• Final trips
• Shots cleared
• AR started
The counters are cumulative and they update automatically according to the operations of the auto-
recloser function. They can be found in the
Statistics tab at Control
→
Auto-recloser
→
Registers.
5.4.5 Cold load pick-up (CLPU)
The cold load pick-up function is used for detecting so-called cold load situations, where a loss of load
diversity has occured after distribution has been re-energized. The characteristics of cold load
situations vary according to the types of loads individual feeders have. This means that this function
needs to be set specifically according to the load type of the feeder it is monitoring. For example, in
residential areas there are relatively many thermostat-controlled devices (such as heating and cooling
machinery) which normally run in asynchronous cycles. When restoring power after a longer power
outage, these devices demand the full start-up power which can cause the inrush current to be
significantly higher than what the load current was before the outage. This is uncommon in industrial
environments since the restoring of the production process takes several hours, or even days, and the
power level goes back to the level it was before the outage. However, some areas of the industrial
network may find the cold load pick-up function useful.
The operating decisions are based on phase current magnitudes and magnitude changes which the
function constantly measures. The blocking signal and the setting group selection control the operating
characteristics of the function during normal operation, i.e. the user or user-defined logic can change
function parameters while the function is running.
The outputs of the function are the CLPU ACT and BLOCKED signals. The cold load pick-up function
uses a total of eight (8) separate setting groups which can be selected from one common source.
The operational logic consists of the following:
• input magnitude processing
• threshold comparator
• block signal check
• time delay characteristics
• output processing.
The inputs for the function are the following:
• setting parameters
• digital input signals
• measured and pre-processed current magnitudes.
The function outputs the CLPU ACT and BLOCKED signals which can be used for direct I/O controlling
and user logic programming. The function generates general time-stamped ON/OFF events to the
common event buffer from each of the two (2) output signals. The time stamp resolution is 1 ms. The
function also provides a resettable cumulative counter for the CLPU ACT and BLOCKED events.
The following figure presents a simplified function block diagram of the cold load pick-up function.
A
AQ
Q-F215
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Instruction manual
Version: 2.04
329
