Open Phase Protection For Transformer, Lines Or Generators And Circuit Breaker Head Flashover Protection For Generators - ABB RELION 670 Series Applications Manual

1MRK 504 152-UEN B
1. select positive sequence current as measuring quantity for this CVGAPC function
2. make sure that the base current value for CVGAPC function is equal to the generator rated
current
3. set k = 37.5 for the IEC standard or k = 41.4 for the ANSI standard
4. set
5. set
6. set
7. set
Proper timing of CVGAPC function made in this way can easily be verified by secondary
injection. All other settings can be left at the default values. If required delayed time reset for
OC1 step can be set in order to insure proper function operation in case of repetitive overload
conditions.
Furthermore the other built-in protection elements can be used for other protection and
alarming purposes.
In the similar way rotor overload protection in accordance with ANSI standard can be achieved.
11.1.3.4 Open phase protection for transformer, lines or generators and circuit
breaker head flashover protection for generators
Example will be given how to use one CVGAPC function to provide open phase protection. This
can be achieved by using one CVGAPC function by comparing the unbalance current with a pre-
set level. In order to make such a function more secure it is possible to restrain it by requiring
that at the same time the measured unbalance current must be bigger than 97% of the
maximum phase current. By doing this it will be insured that function can only pickup if one of
the phases is open circuited. Such an arrangement is easy to obtain in CVGAPC function by
enabling the current restraint feature. The following shall be done in order to insure proper
operation of the function:
1. Connect three-phase currents from the protected object to one CVGAPC instance (for
example, GF03)
2. Set
3. Set
4. Set
5. Set
6. Set base current value to the rated current of the protected object in primary amperes
7. Enable one overcurrent step (for example, OC1)
8. Select parameter
9. Set parameter
10. Set parameter
Proper operation of CVGAPC function made in this way can easily be verified by secondary
injection. All other settings can be left at the default values. However it shall be noted that set
values for restrain current and its coefficient will as well be applicable for OC2 step as soon as
it is enabled.
Furthermore the other built-in protection elements can be used for other protection and
alarming purposes. For example, in case of generator application by enabling OC2 step with
set pickup to 200% and time delay to 0.1s simple but effective protection against circuit
breaker head flashover protection is achieved.
Application manual
A_OC1 = 1/1.162 = 0.7432
C_OC1 = 1/1.162 = 0.7432
B_OC1 = 0.0 and P_OC1 = 2.0
StartCurr_OC1 = 116%
CurrentInput to value UnbalancePh
EnRestrainCurr to On
RestrCurrInput to MaxPh
RestrCurrCoeff to value 0.97
CurveType_OC1 to value IEC Def. Time
StartCurr_OC1 to value 5%
tDef_OC1 to desired time delay (for example, 2.0s)
Section 11
Multipurpose protection
M13088-142 v3
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