M12352-1 v15
Table 63. Thermal overload protection, one time constant LCPTTR/LFPTTR
Function Range or value Accuracy
Reference current (2-400)% of IBase ±1.0% of I
r
Reference temperature (0-300)°C, (0 - 600)°F
±1.0°C, ±2.0°F
Operate time:
22
22
ln
p
Trip Amb
ref
ref
II
t
TT
II
T
σ
,
<
,
,√
EQUATION13000039 V3 EN-US (Equation 1)
T
Trip
= set operate temperature
T
Amb
= ambient temperature
T
ref
= temperature rise above ambient at I
ref
I
ref
= reference load current
I = actual measured current
I
p
= load current before overload occurs
Time constant t = (1–1000)
minutes
IEC 60255-149, ±5.0% or ±200 ms whichever is greater
Alarm temperature (0-200)°C, (0-400)°F ±2.0°C, ±4.0°F
Operate temperature (0-300)°C, (0-600)°F ±2.0°C, ±4.0°F
Reset level temperature (0-300)°C, (0-600)°F ±2.0°C, ±4.0°F
Line differential protection RED670
1MRK 505 379-BEN N
100 Hitachi Power Grids
© Copyright 2017 Hitachi Power Grids. All rights reserved
To Next Page
Loading...
