Trip Function; Close Characteristics; Settings; Data Buffer - Eaton MPCV Series Instruction Booklet

Instruction Bulletin
Instruction Booklet IB02402001E
Page 4 Effective: September 2004
December 2010

Trip Function

Figure 16 diagrams the current-induced trip characteristics.
The positive sequence current l1 is multiplied by the cosine
of the angle of its phasor related to V1N. If the resulting sign
is negative, then reverse power-flow is indicated. The trip
level (l1COSØ) for this can be adjusted from .05 to 5% of
rated current. The cosine multiplication operation results in
the straight line which is perpendicular to the phasor.
A selection to a watt-var trip curve can be made through the
hand-held pendant which will permit 3-phase balanced trip
characteristics, as well as tripping when the negative
sequence voltage exceeds .06 P.U.
The BN function can be initialized to modify the characteris-
tics and timing of the reverse-current trip conditions. This
adds to the basic detection requirements that the true rms
value of the reverse current exceeds some settable threshold
between 50% and 250% of the protector CT rating. When
the magnitude of the reverse current is less than the settable
threshold, a trip will occur if the condition exists for an
adjustable time period of 0 to 5 minutes. The BN function is
standard on all MPC relays.

Close Characteristics

Figure 14 also diagrams the voltage regions for close, float
and trip operation when the protector is open. Under extreme
conditions when the protector is open, a trip is called for to
prevent a dangerous manual close operation. With the protec-
tor open and the network and transformer voltages normal
and balanced, positive sequence phasing voltage (V1P) is
measured. If V1P is in the close region, the relay makes its
close contact. If V1P is not in the close region, but is less than
.06 P.U., then the float is called for, as this voltage difference
is not deemed dangerous regardless of the phase relation-
ships, and manual close of the protector would not exceed the
breaker capacity. If V1P is greater than .06 P.U. and does not
lie in the close region, the trip is called for to prevent manual
closing. The relay also calls for trip under all rolled and crossed
phase conditions, even when either the transformer side or the
network side of the protector is de-energized.
The close contact will close only in the quadrant defined by
the two lines, termed master and phasing. The phasing line,
emanating from 0, defines a minimum phase angle of the
phasing voltage ahead of the network voltage for closing,
which is selectable at +5, -5, -15 or -25 degrees. The master
line sets a minimum difference between the transformer and
network voltage, settable from .0008 to .02 P.U. at 0
degrees (in phase). This line exhibits a slope of 7.5 degrees.
If the network side is de-energized, and the transformer side
is energized, the close contact will close, if V1N is less than
.1 P.U., and V2N is less than .06 P.U., and V1P exceeds .8
P.U. Note that, as stated before, if V2P exceeds .2 P.U., then
the trip contact will close, indicating crossed phases on either
the transformer side or the network side. Also note, that if
the phases are crossed on both the transformer and the net-
work side, V2P could be very close to or equal to zero, but
the trip contact will close as V1N is less than 0.1 P.U. and
V1P is less than .8 P.U.
The other closing curve characteristic option available is the curved
line closing curve which maintains the same value of phasing volts
from the -25 to +90 degree quadrants (refer to Figure 15 ).
Any close conditions must exist for 500 ms before the close
contact will close.
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Instruction for the
Cutler-Hammer Type MPCV
Network Protection Relay

Settings

All settings can be altered through a digital control pendant
which plugs into the unit while mounted on the network pro-
tector breaker. When not in use, the pendant may be stored
separate from any network protector location, most conve-
niently with the network protector test kit. While the pendant
is plugged in, actual trip and close operations will be inhibited
and the amber float light will flash. The pendant has a display
for the readout of the set points and a keyboard to set them.
Refer to Figure 1 for pendant layout.

Data Buffer

There are two data buffers for event logging. These buffers
are volatile and they can be lost when power is lost or when
downloaded to PowerNet
1. Waveform Capture Buffer is a buffer that contains 16
cycles of data sampled 32 times per power cycle that
includes the transformer and network voltages, currents
and trip (reasons) flags which is about 9.3 kb total. This
single buffer capable of storing one trip event is stored in
a volatile memory until the next download or power loss
occurs. The data are captured in two ways.
Trip Buffer is created automatically by the MPCV upon detec-
tion of any trip condition. This buffer remains in the MPCV
until PowerNet unlocks (frees) the buffer, which it will do
once it completes downloading of all the data, or upon a com-
plete loss of power. Note that any subsequent trips of the
MPCV with a filled trip buffer in the locked state will NOT be
captured, i.e., the Trip buffer is NOT overwritten by
subsequent trips.
Waveform Buffer is requested by user using the PowerNet
that can also be cleared upon downloading the information,
but unlike the trip buffer, it also can be written over by a
subsequent user waveform capture request. This buffer is
volatile and sensitive to power loss.
2. Time-Stamp Trip Buffer — Each trip operation of the relay
is logged in this buffer, with each trip generating a 6-
message INCOM
time stamp and state of all the trip flags for the particular
trip. No sampled waveforms are part of this buffer. The
MPCV can store up to 15 time stamped events before its
buffer queue is filled up. As the TSE buffer(s) is/are read
by PowerNet, they can be entered into the PowerNet
Event Log, as they are deleted from the MPCV queue.
Should PowerNet remain disconnected from a relay for
extended times, and should that MPCV trip more than 15
times, the most recent 15 events will remain stored in
the relay so long as power is not removed from the relay.
For more information visit: www.EatonElectrical.com
Instructions for the Eaton Type
MPCV Network Protection Relay
Event Log.
buffer (18 bytes). This records the
IB02402001E