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Section 4
1MAC050144-MB C
Protection functions
248
615 series ANSI
Technical Manual
4.2.5.9
Technical data
Table 254: 27PS Technical data
4.2.6
Voltage per Hertz Protection, 24
4.2.6.1
Identification
4.2.6.2
Function Block
Figure 117:
Function Block
4.2.6.3
Functionality
The overexcitation protection 24 is used to protect the generators and power transformers
against an excessive flux density and saturation of the magnetic core.
The function calculates the V/f ratio (volts/hertz) proportional to the excitation level of the
generator or transformer and compares this value to the setting limit. The function picks
Characteristic
Value
Pickup accuracy
Depending on the frequency of the voltage
measured: f
n
±2Hz
±1.5% of the set value or ±0.002 x V
n
Pickup time
12
1.
Pickup value
= 1.0 x V
n
, Positive sequence voltage before fault = 1.1 x V
n
, f
n
= 60 Hz, positive sequence
undervoltage with nominal frequency injected from random phase angle, results based on statistical distribu-
tion of 1000 measurements
2. Includes the delay of the signal output contact
Minimum
Typical
Maximum
V
Fault
= 0.99 x set
Pickup value
V
Fault
= 0.9 x set
Pickup
value
51 ms
43 ms
53 ms
45 ms
54 ms
46 ms
Reset time
< 40 ms
Reset ratio
Depends of the set
Relative hysteresis
Retardation time
< 35 ms
Trip time accuracy in definite time mode
±1.0% of the set value or ±20 ms
Suppression of harmonics
DFT: -50 dB at f = n x f
n
, where n = 2, 3, 4, 5,…
Function Description
IEC 61850
Identification
IEC 60617
Identification
ANSI/IEEE C37.2
device number
Overexcitation protection
OEPVPH
U/f>
24
TRIP
PICKUP
V3P
24
BLOCK
BLK_PICKUP
BLK_TRIP
FR_TIMER
BLK_RESTART
COOL_ACTIVE
I3P
Содержание 615 Series ANSI
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Страница 29: ...1MAC050144 MB C Section 615 series ANSI 22 Technical Manual ...
Страница 389: ...Section 4 1MAC050144 MB C Protection functions 382 615 series ANSI Technical Manual ...
Страница 485: ...Section 6 1MAC050144 MB C Supervision functions 478 615 series ANSI Technical Manual ...
Страница 635: ...Section 10 1MAC050144 MB C Other functions 628 615 series ANSI Technical Manual ...
Страница 707: ...Section 15 1MAC050144 MB C Applicable standards and regulations 700 615 series ANSI Technical Manual ...
Страница 711: ...Section 16 1MAC050144 MB C Glossary 704 615 series ANSI Technical Manual ...
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