IG-150-EN version 04; 03/10/16
98
Protection functions. Description and settings General instructions
ekor.rps
4.21.4. Heating curves
The heating curve is calculated from the following formula:
Being T
f
= nal temperature
T
i
= initial temperature
t = time
τ1 = Heating time constant
For Ti = 0 the formula is reduced
As in
The heating curve is:
The next gure gives as an example, the heating curves,
with 3 min time constant, for I/I
0
= 1 and for I/I
0
= 2.
Figure 4.33. Heating curves
4.21.5. Cooling curves
The cooling curve is calculate from the following:
Being: T
f
=nal temperature
T
i
=initial temperature
t=time
τ2=cooling time constant
Starting from T
i
= 1 (100 in %), tripping temperature, in
order to arrive to a nal temperature of T
f
= 0 (that is with
current I = 0), the formulae is reduced to:
Example: Cooling curve with 3 min constant.
Figure 4.34. Cooling curves
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