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Transformer protection RET650
Product version: 1.1
Table 28. Thermal overload protection, two time constants TRPTTR
Function
Base current 1 and 2
Operate time:
æ
ö
2
2
-
I
I
p
ç
÷
= ×
t
t
ln
ç
÷
2
2
-
I
I
è
ø
b
(Equation 1)
EQUATION1356 V1 EN
I = I
measured
Alarm level 1 and 2
Operate current
Reset level temperature
Table 29. Breaker failure protection CCRBRF
Function
Operate phase current
Reset ratio, phase current
Operate residual current
Reset ratio, residual current
Phase current level for
blocking of contact function
Reset ratio
Timers
Operate time for current
detection
Reset time for current
detection
54
Range or value
(30–250)% of IBase
I
= load current before
p
overload occurs
Time constant τ = (1–500)
minutes
(50–99)% of heat content
trip value
(50–250)% of IBase
(10–95)% of heat content
trip
Range or value
(5-200)% of lBase
> 95%
(2-200)% of lBase
> 95%
(5-200)% of lBase
> 95%
(0.000-60.000) s
35 ms typically
10 ms maximum
1MRK 504 127-BEN -
Issued: February 2011
Accuracy
± 1.0% of I
r
IEC 60255–8, class 5 + 200 ms
± 2.0% of heat content trip
± 1.0% of I
r
± 2.0% of heat content trip
Accuracy
± 1.0% of I
at I £ I
r
± 1.0% of I at I > I
-
± 1.0% of I
at I £ I
r
± 1.0% of I at I > I
-
± 1.0% of I
at I £ I
r
± 1.0% of I at I > I
-
± 0.5% ±10 ms
-
-
r
r
r
r
r
r
ABB
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