![background image](http://html.mh-extra.com/html/abb/relion-615-series/relion-615-series_technical-manual_2395437.webp)
grounding. For example, the angle is about 145 degrees for a high-resistance-grounded
unit generator.
The equation defines the "operate" and "restrain" regions of the protection. The third
harmonic differential protection operates according to the following equation.
V
V
V
3
3
3
H T
H N
H N
Beta
_
_
_
+
≥
⋅
GUID-6F60D909-1976-4A51-A8F5-97370554C78A V1 EN
(Equation 51)
V
3
H N
_
Neutral side third harmonic voltage phasor
V
3
H T
_
Terminal side third harmonic voltage phasor
Beta
Setting to achieve a required degree of security under healthy conditions
V
V
3
3
H T
H N
_
_
+
Magnitude of the third harmonic differential voltage
Beta
H N
⋅
V
3
_
Magnitude of the third harmonic bias (restrain) voltage
Factor
Beta
, which is a setting, can be determined from the condition.
Beta
K
H N
H T
H N
⋅
+
=
V
V
V
3
3
3
_
_
_
GUID-57727225-84D4-4B41-B618-05351CE22A7E V1 EN
(Equation 52)
K is the security factor, for example K = 1.5.
must be satisfied in the normal,
healthy condition of the protected generator, with a high enough value for K, so that no
unwanted operation of the protection should be expected, regardless the load on the
generator.
To assure a reliable functioning of the protection, it is necessary that the
generator produces third harmonic voltage which is at least 1% of the
generator rated voltage.
As phase-to-phase voltages do not contain a third harmonic component, in situations
where the VTs on the terminal side are connected between phase-to-phase, the differential
protection in
cannot work. In such case, the
Voltage selection
setting is set to
"No Voltage" and 27/59THN operates as a simple neutral side third harmonic
undervoltage protection.
1MAC059074-MB A
Section 4
Protection functions
615 series ANSI
431
Technical Manual
Содержание Relion 615 series
Страница 1: ... RELION PROTECTION AND CONTROL 615 series ANSI Technical Manual ...
Страница 2: ......
Страница 39: ...Section 17 Glossary 1181 Table of contents 615 series ANSI 33 Technical Manual ...
Страница 40: ...34 ...
Страница 64: ...58 ...
Страница 210: ...3 19 4 Settings Section 3 1MAC059074 MB A Basic functions 204 615 series ANSI Technical Manual ...
Страница 216: ...210 ...
Страница 884: ...878 ...
Страница 1038: ...1032 ...
Страница 1136: ...1130 ...
Страница 1172: ...1166 ...
Страница 1180: ...1174 ...
Страница 1186: ...1180 ...
Страница 1192: ...1186 ...
Страница 1193: ...1187 ...
Страница 1194: ......
Страница 1195: ......