ABB RET670 Product Manual page 62

Transformer protection RET670
Pre-configured
Product version: 1.1
Table 36. Sensitive directional residual overcurrent and power protection SDEPSDE ,
continued
Function
Operate time, non
directional residual over
current
Reset time, non
directional residual over
current
Operate time, start
function
Reset time, start function
Table 37. Thermal overload protection, two time constants TRPTTR
Function
Base current 1 and 2
Operate time:
æ ö
2 2
-
I I
p
t ç ÷
= ×
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
62
Range or value
60 ms typically at 0 to 2 x I
60 ms typically at 2 to 0 x I
150 ms typically at 0 to 2 x I
50 ms typically at 2 to 0 x I
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
1MRK 504 091-BEN B
Issued: June 2010
Accuracy
-
set
-
set
-
set
-
set
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
ABB