12.3.2.2
User-programmable inverse-time characteristics for undervoltage
protection
The user can define curves by entering parameters into the standard formula:
t s
k A
B
V
V
V
C
D
E
=
⋅
×
<
<
−
+
-
GUID-4A433D56-D7FB-412E-B1AB-7FD43051EE79-ANSI V2 EN
(Equation 42)
t[s] trip time in seconds
A
the set value of
Curve parameter A
B
the set value of
Curve parameter B
C
the set value of
Curve parameter C
D
the set value of
Curve parameter D
E
the set value of
Curve parameter E
V
measured voltage
V< the set value of
Pickup value
k
the set value of
Time multiplier
12.3.2.3
IDMT curve saturation of undervoltage protection
For the undervoltage IDMT mode of operation, the integration of the trip time does not
start until the voltage falls below the value of
Pickup value
. To cope with discontinuity
characteristics of the curve, a specific parameter for saturating the equation to a fixed
value is created. The
Curve Sat Relative
setting is the parameter and it is given in percents
compared with
Pickup value
. For example, due to the curve equation B, the characteristics
equation output is saturated in such a way that when input voltages are in the range from
Pickup value
to
Curve Sat Relative
in percents under
Pickup value
, the equation uses
Pickup value
* (1.0 -
Curve Sat Relative
/ 100 ) for the measured voltage. Although, the
curve A has no discontinuities when the ratio V/V> exceeds the unity,
Curve Sat Relative
is set for it as well. The
Curve Sat Relative
setting for curves A, B and C is 2.0 percent.
However, it should be noted that the user must carefully calculate the curve characteristics
concerning also discontinuities in the curve when the programmable curve equation is
used. Thus, the
Curve Sat Relative
parameter gives another degree of freedom to move the
inverse curve on the voltage ratio axis and it effectively sets the maximum trip time for the
IDMT curve because for the voltage ratio values affecting by this setting, the operation
time is fixed, that is, the definite time, depending on the parameters but no longer the
voltage.
Section 12
1MRS240050-IB C
General function block features
616
REF615R
Technical Manual
Содержание RELION REF615R
Страница 1: ... RELION PROTECTION AND CONTROL REF615R Technical Manual ...
Страница 2: ......
Страница 27: ...Section 18 Glossary 653 Table of contents REF615R 21 Technical Manual ...
Страница 28: ...22 ...
Страница 36: ...30 ...
Страница 46: ...40 ...
Страница 115: ...3 15 4 Settings 1MRS240050 IB C Section 3 Basic functions REF615R 109 Technical Manual ...
Страница 118: ...112 ...
Страница 318: ...312 ...
Страница 388: ...382 ...
Страница 456: ...450 ...
Страница 520: ...514 ...
Страница 652: ...646 ...
Страница 656: ...650 ...
Страница 658: ...652 ...
Страница 663: ...657 ...