6.38 Demand of peak currents
6.38.1 I thermal demand
This measurement is used to simulate a bimetallic system, known from the Maximum Demand ammeter,
which is specifically suited for indication of thermal loads in conjunction with cables, transformers, etc.
It is possible to have two different readouts shown in the display. The first readout is called I thermal demand.
This readout shows the average maximum peak current over an adjustable time interval.
Be aware that the calculated average is NOT the same as the average current over time. The I
thermal demand value is an average of the MAXIMUM PEAK current in the adjustable time in-
terval.
The measured peak currents are sampled once every second, and every 6 seconds an average peak value is
calculated. If the peak value is higher than the previous maximum peak value, it is used to calculate a new
average. The thermal demand period will provide an exponential thermal characteristic.
The time interval in which the average maximum peak current is calculated can be adjusted in parameter
6840. The value can also be reset. If the value is reset, it will be logged in the event log and the readout in the
display is reset to 0.
6.38.2 I max. demand
The second readout is called I maximum demand, and shortened in the unit, I max. demand. The readout
displays the newest maximum peak current value. When a new maximum peak current is detected, the value
is saved in the display. The value can be reset in menu 6843. If the value is reset, it will be logged in the
event log.
The two reset functions will also be available as commands through M-Logic.
Display readout is updated with an interval of 6 seconds.
AGC 100 Designer's Reference Handbook
4189340766 UK
Additional functions
DEIF A/S Page 105 of 152
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