Ampcontrol IPD - Page 96

Ampcontrol Pty Ltd – ABN 28 000 915 542
IPD USER MANUAL
IPDB014 Version 14 – SEP/2020
Uncontrolled Copy - Refer to Ampcontrol Website for Latest Version
Page 96 of 96
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– NOT TO BE REPRODUCED IN PART
Also,
m 1800 
Where:
m
is the time multiplier setting, programmed in the IPD menu.
After a trip occurs, the thermal time constant is modified by the cooling modifier:
torCoolingFac
cold

 
NOTE: the function which has been published elsewhere in this document for motor overload is:









1238.1
ln1800\
2
2
I
hI
mLTriptimeMO
Where:
m
is the time multiplier
h is 0 for ‘cold’ and 1 for ‘hot’
These two algorithms are mathematically and operationally identical. For purposes of demonstrating
conformance to 3.1.2 of IEC 60255-8, the algorithm has been rewritten for clarity.
Equivalence with the IEC 60255-8 is established with:
I
B
= 1.0
k= 1.0601

= 1800
m
Resultant values of (based on the range of m values) is 9 ≤

≤ 1800 (0.005 ≤
m
≤ 1.0).
The overall error in tripping accuracy for Motor Overload is 5%.