ABB REU 610 Technical Reference Manual page 30

REU 610
30
Voltage Relay
Technical Reference Manual - ANSI Version
IDMT calculation does not pickup until the deviation between the measured
voltage and the setting value exceeds 3 percent. The operate time accuracy
stated in technical data applies when the deviation is 10 percent or higher.
Characteristics of the overvoltage elements
The IDMT characteristic curve groups A and B are designed for overvoltage
elements 59P-1 and 59P-2/47. Elements 59P-1 and 59P-2/47 can be
configured to use different characteristics. The relationship between time and
voltage at IDMT characteristic can be expressed as follows:
×
TD 480
t[s]=
−
U 59P

×
32

59P

t = operate time
TD = time dial 59P-1 TD or 59P-2 TD
U = measured voltage
59P = set pickup value 59P-1 or 59P-2/47
p = constant (see Table 5.1.4.6.-2)
The A- and B-type characteristics are illustrated in Fig. 5.1.4.6.-1 and
Fig. 5.1.4.6.-2.
If the ratio between the voltage and the set value is higher than
1.6, the operate time is the same as when the ratio is 1.6.
Characteristic of the undervoltage elements
The IDMT characteristic curve group C is designed for undervoltage elements
27P-1 and 27P-2/27D. Elements 27P-1 and 27P-2/27D can be configured to
use different characteristics. The relationship between time and voltage at
IDMT characteristic can be expressed as follows:
×
TD 480
t[s]=
−
 27P U
×
32

27P

t = operate time
TD = time dial 27P-1 TD or 27P-2 TD
U = measured voltage
27P = set pickup value 27P-1 or 27P-2/27D
p = constant (see Table 5.1.4.6.-2)
The C-type characteristic is illustrated in Fig. 5.1.4.6.-3.
+ 0.05
p

−
0.5


p

−
0.5


1MRS755972
(3)
(4)