GE DGP Series, Инструкция по эксплуатации

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DGP Digital Generator Protection System GE Power Management
2.3 PROTECTION FUNCTION SETTINGS 2 CALCULATION OF SETTINGS
2
2.3.13 OVERVOLTAGE 59
Algorithm:
T2 =
K
seconds
T3 = no intentional time delay
where:
T1 = Operating time for CURVE #1 (see Figure 2–15: 59 TIME-VOLTAGE CHARACTERISTICS)
T2 = Operating time for CURVE #2 (the characteristic of optional curve #2 is definite time providing the
operating time equal to K seconds if
V
1
>
V
PU
)
T3 = Operating time of optional instantaneous function if
V
1
>
V
PU
K
= time factor (Setting 1504: TIME FAC)
V
1
= positive-sequence voltage (phase-phase)
V
PU
= overvoltage pickup (Setting 1503: INV PICKUP)
V
IPU
= instantaneous overvoltage pickup (Setting 1506: INST PU)
Reset Time: Linear reset (1.4 seconds maximum)
Characteristics: Figure 2–15: 59 TIME-VOLTAGE CHARACTERISTICS shows the CURVE #1 for selected val-
ues of
K
. The curve for any other
K
setting can be derived using the above algorithm.
This function should be set with a safe margin below the overvoltage capability of the protected equipment.
Function 59 can provide backup to function 24T.
For the sample generator system, set 59 using criteria similar to 24T settings except with lower sensitivity and
higher operating time.
Set
V
PU
= 1.1
×
NOM VOLT = 1.1
×
114.3 = 126 volts
For determining the time factor
K
(assuming CURVE #1 is used), use an operating time of about 45 seconds at
115% of PICKUP voltage.
Voltage (
V
) = 1.15
×
126 = 144.9 volts
Time Factor
K
=
T1
K
V
1
V
PU
----------
1 –
--------------------
seconds
=
45
144.9
126
--------------- 1 –
 
 
⋅
6.75 =