ABB RET670 - Thermal Overload Protection, Two Time Constants TRPTTR

Table 48. 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:
2 2
2 2 2
ln
p
Trip Amb
p ref
ref
I I
t
T T
I I I
T
t
-
=
-
- - ×
é ù
ê ú
ê ú
ê ú
ê ú
ë û
EQUATION13000039 V2 EN (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 60255-8, ±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
Table 49. Thermal overload protection, two time constants TRPTTR
Function
Range or value Accuracy
Base current 1 and 2 (30–250)% of IBase ±1.0% of I
r
Operate time:
2 2
2 2
p
ref
I I
t ln
I I
t
æ ö
-
ç ÷
= ×
ç ÷
-
è ø
EQUATION1356 V2 EN (Equation 2)
I = actual measured current
Ip = load current before overload
occurs
Iref = reference load current
I
p
= load current before overload
occurs
Time constant τ = (0.10–500.00)
minutes
±5.0% or ±200 ms whichever is greater
Alarm level 1 and 2 (50–99)% of heat content operate
value
±2.0% of heat content trip
Operate current (50–250)% of IBase ±1.0% of I
r
Reset level temperature (10–95)% of heat content trip ±2.0% of heat content trip
Transformer protection RET670 2.0
1MRK 504 141-BEN C
Product version: 2.0
ABB 67