4–51
System Setup and Setpoints – 4
24 Volts/Hz Overexcitation
NOTE:
Two or four voltage inputs are available
for the M-3311A. The Voltage Input can
be a phase voltage input or voltage
generated from a broken delta VT con
-
nection. 81O/U, 27, and 24 Functions
are only available if the voltage input is
connected to the phase voltage. If the
voltage input is connected to phase volt-
age, Function 59G will be unavailable.
Function 59G is only available if the
voltage input is connected to a broken
delta VT. If voltage input is connected to
broken delta VT, Functions 81O/U, 27,
and 24 will be unavailable.
The 24 Volts-Per-Hertz (V/Hz) function provides
over-excitation protection for the transformer. As the
volts per hertz level rises above a transformer’s limit,
leakage flux increases. The leakage flux induces
current in the transformer support structure causing
rapid localized heating.
In power plant applications, over-excitation can
occur due to sudden tripping of the generator as a
result of faults and other abnormal conditions.
In Extra High Voltage (EHV) applications, an incor
-
rectly switched line can lead to over-excitation at
tapped transformers due to combined capacitance.
In transmission and distribution applications, sud-
den loss of load or improper capacitor/reactor
switching may result in overexcitation.
This function provides two Definite Operating Time
setpoints, four families of Inverse Time curves widely
used in the industry (see Appendix D, Figures D1 to
D4), and a linear reset rate programmable to match
specific cooling characteristics of the transformer.
The V/Hz function provides reliable measurements
of V/Hz for a frequency range of 10–80 Hz.
When applied for generator and unit transformer
protection, the first task in setting this relay function
is to determine the desired protective levels and
times. This can be accomplished by combining the
V/Hz limit curves of the transformer and the associ
-
ated generator on one graph and simplifying the re-
sult into one curve to coordinate with the protection.
Example of Transformer limits:
• Full Load V/Hz = 1.05 PU (HV terminals)
• No Load V/Hz = 1.10 PU (HV terminals)
NOTE:
The curves must be on the same volt-
age base to be combined on one graph.
An example is shown in Figure 4-28,
Example of Capability and Protection
Curves. The manufacturer of the genera-
tor and transformer will provide these
over-excitation capability limits.
Depending on these characteristics, they can best
be matched by one of the four families of inverse
time curves, alone or in conjunction with definite
time setpoints. Coordination of capabilities and
protection is achieved when the time between the
relay operation and the capability limit is sufficient
for the breakers to open and de-energize the units.
This coordination time is read vertically between
the two curves at any given V/Hz value.
Figure 4-28, Example of Capability and Protection
Curves, illustrates a composite graph of gen-
erator limits, transformer limits, a chosen inverse
time curve, inverse time pickup, and definite time
setpoint. While inverse time curve selection may
provide more selective and sensitive protection,
a traditional two-step protection scheme may be
realized by using the two definite time functions
(24DT #1 and #2), and disabling the inverse (24IT)
element.
Содержание M?3311A
Страница 1: ...Instruction Book M 3311A Transformer Protection Relay ...
Страница 30: ... 29 M 3311A Transformer Protection Relay This Page Left Intentionally Blank ...
Страница 55: ...M 3311A Instruction Book 1 6 This Page Left Intentionally Blank ...
Страница 67: ...M 3311A Instruction Book 2 12 Path Monitor Metering ll Figure 2 9 Metering II Screen 4 Winding ...
Страница 87: ...M 3311A Instruction Book 2 32 This Page Left Intentionally Blank ...
Страница 89: ...M 3311A Instruction Book 3 2 Figure 3 2 IPScom Main Screen ...
Страница 93: ...M 3311A Instruction Book 3 6 Figure 3 8 Terminal Window Figure 3 7 IPScom Modem Communication Dialog Screen ...
Страница 99: ...M 3311A Instruction Book 3 12 Path Monitor Metering ll Figure 3 14 Metering II Screen 4 Winding ...
Страница 103: ...M 3311A Instruction Book 3 16 Path Monitor Phasor Diagram F87T Figure 3 18 Phasor Diagram F87T 4 Winding ...
Страница 107: ...M 3311A Instruction Book 3 20 Figure 3 22 Setup System Dialog Screen 2 3 Winding ...
Страница 108: ...IPScom 3 3 21 Figure 3 23 Setup System Dialog Screen 4 Winding ...
Страница 112: ...IPScom 3 3 25 Figure 3 29 I O Map Screen 4 Winding ...
Страница 114: ...IPScom 3 3 27 Figure 3 31 Display All Setpoints Screen 4 Winding ...
Страница 119: ...M 3311A Instruction Book 3 32 Figure 3 38 View Sequence of Events Recorder Screen ...
Страница 127: ...M 3311A Instruction Book 3 40 This Page Left Intentionally Blank ...
Страница 150: ...4 23 System Setup and Setpoints 4 Figure 4 14 Setup Sequence of Events Recorder Dialog Screen ...
Страница 163: ...4 36 M 3311A Instruction Book Figure 4 15 IPScom Relay Setup System Dialog Screen 2 3 Winding ...
Страница 164: ...4 37 System Setup and Setpoints 4 Figure 4 16 IPScom Relay Setup System Dialog Screen 4 Winding ...
Страница 166: ...4 39 System Setup and Setpoints 4 Figure 4 18 IPScom Selection Screen for Input Settings ...
Страница 179: ...4 52 M 3311A Instruction Book Figure 4 28 Example of V Hz Capability and Protection Curves ...
Страница 187: ...4 60 M 3311A Instruction Book Figure 4 33 49 Function Overload Curves ...
Страница 229: ...4 102 M 3311A Instruction Book Table 4 5 Transformer Connections ...
Страница 231: ...4 104 M 3311A Instruction Book Table 4 7 Custom Transformer and CT Configuration ...
Страница 233: ...4 106 M 3311A Instruction Book CONNECTION EXAMPLES Figure 4 72 Typical Transformer Differential Application ...
Страница 234: ...4 107 System Setup and Setpoints 4 AUXILIARY TRANSFORMER EXAMPLE Figure 4 73 Delta ac Wye Wye CT Connection Diagram ...
Страница 236: ...4 109 System Setup and Setpoints 4 GSU TRANSFORMER EXAMPLE Figure 4 75 Wye Delta ac Delta ac CT Connection Diagram ...
Страница 243: ...M 3311A Instruction Book 5 6 Figure 5 5 Mounting Dimensions for GE L 2 Cabinet H3 and H4 ...
Страница 275: ...M 3311A Instruction Book 5 38 Dip Switch J46 J60 J61 J5 J20 J21 J22 J18 Figure 5 34 M 3311A Circuit Board Standard I O ...
Страница 383: ...A 50 M 3311A Instruction Book This Page Left Intentionally Blank ...
Страница 389: ...M 3311A Instruction Book B 6 This Page Left Intentionally Blank ...
Страница 393: ...D 2 M 3311A Instruction Book Figure D 1 Volts Hz 24IT Inverse Curve Family 1 Inverse Square ...
Страница 394: ...Inverse Time Curves Appendix D D 3 Figure D 2 Volts Hz 24IT Inverse Family Curve 2 ...
Страница 395: ...D 4 M 3311A Instruction Book Figure D 3 Volts Hz 24IT Inverse Time Curve Family 3 ...
Страница 396: ...Inverse Time Curves Appendix D D 5 Figure D 4 Volts Hz 24IT Inverse Curve Family 4 ...
Страница 399: ...D 8 M 3311A Instruction Book Figure D 5 Definite Time Overcurrent Curve ...
Страница 400: ...Inverse Time Curves Appendix D D 9 Figure D 6 Inverse Time Overcurrent Curve ...
Страница 401: ...D 10 M 3311A Instruction Book Figure D 7 Very Inverse Time Overcurrent Curve ...
Страница 402: ...Inverse Time Curves Appendix D D 11 Figure D 8 Extremely Inverse Time Overcurrent Curve ...
Страница 439: ...F 28 M 3311A Instruction Book This Page Left Intentionally Blank ...
Страница 449: ...This Page Left Intentionally Blank ...