ABB REU 610 Technical Reference Manual page 31

1MRS755769
Voltage Relay
Technical Reference Manual
Table 5.1.4.6.-1 Operation mode setting parameters
Protection Parameter
stage
U> S3
U>>/U > S11
2
U< S15
U<</U < S22
1
At IDMT characteristic, the operate time of the stage is dependent on the voltage
value: the greater the deviation from the setting value, the shorter the operate time.
Three time/voltage curve groups are available: A, B and C.
An overvoltage stage starts when the measured voltage exceeds the setting value of
the stage. An undervoltage stage starts when the measured voltage drops below the
setting value of the stage. However, the IDMT calculation does not start 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 stages
The IDMT characteristic curve groups A and B are designed for overvoltage stages
U> and U>>/U >. Stages U> and U>>/U
2
characteristics. The relationship between time and voltage at IDMT characteristic
can be expressed as follows:
×
k 480
t[s]=
−
U U>

×
32

U>

t = operate time
k = time multiplier k> or k>>
U = measured voltage
U> = set start value U> or U>>/U
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.
Setting
0 = definite time
1 = curve A
2 = curve B
0 = definite time
1 = curve A
2 = curve B
0 = definite time
1 = curve C
0 = definite time
1 = curve C
> can be configured to use different
2
+ 0.05
p

−
0.5


>
2
REU 610
(3)
31