Lpttr - ABB REQ650 Product Manual

ABB
Breaker protection REQ650 ANSI
Product version: 1.1
Table 28. Thermal overload protection, one time constant LPTTR (26)
Function
Reference current
Reference temperature
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 = actual measured
current
I = load current before
p
overload occurs
I = base current, IBase
b
Alarm temperature
Trip temperature
Reset level temperature
Range or value
(0-400)% of IBase
(0-600)°C
Time constant t = (0–
1000) minutes
(0-200)°C
(0-600)°C
(0-600)°C
1MRK 505 269-BUS -
Issued: April 2011
Accuracy
± 1.0% of I
n
± 1.0°C
IEC 60255-8, class 5 + 200 ms
± 2.0% of heat content trip
± 2.0% of heat content trip
± 2.0% of heat content trip
61