Ac Line Interruptions - Eaton MP-3000 Instruction Leaflet

by transitions - they run for the set time, which may be less than or
greater than the time of transition. These timers include:
• Ground fault start delay (GFSD, P3L2)
• Instantaneous overcurrent start delay (IOCSD, P3L5)
• Jam trip and alarm start delay (JMSD, P3L7)
• Underload trip and alarm start delay (ULSD, P3L10)
• Unbalance trip and alarm start delay (UBSD, P3L13)
Also, at the time of the start, the counters and timers for the jogging
controls are updated. These include starts allowed per time (ST/T and
T/ST, P5L1 and P5L2), time between starts (TBS, P5L3), and number
of cold starts allowed (NOCS, P5L4). If a jogging limit is reached, only
a STEX alarm occurs, but if the limit still applies when the motor next
stops, the motor is tripped and blocked at that time.
9.2.3 Run Cycle
When the transition occurs, the MP-3000 declares the run state for
the motor. A RUN message is displayed and communicated to the
PowerNet host.
9.2.4 Run Delays
Note that run delays on trip and alarm functions do not have any
particular relationship to the transition to the RUN state of the relay.
Run delays are pickup delays on active functions, which are able to
measure as soon as the respective start delay has expired. Refer to
Subsection 9.2.2 for start delay details. The primary function of run or
pickup delays is to prevent nuisance tripping. These delays are:
• Ground fault run delay (GFRD, P3L3);
• Jam trip run delay (JMTR, P3L8);
• Underload run delay (ULTR, P3L11);
• Phase unbalance alarm run delay (UBTR, P3L14);
• Jam alarm run delay (JMAR, P4L4);
• Underload alarm run delay (ULAR, P4L6);
• Unbalance alarm run delay (UBAR, P4L8); and
• Load shed delay for pickup and dropout (LSDL, P9L3).
9.2.5 Stop Cycle
The run cycle continues until the motor current level falls below the
Stop Current Threshold (STOP XX, P1L9) setting current on all three
phases. Then, a stop is declared. Jogging limits, as listed in Sub-
section 9.2.2, and the antibackspin time delay (ABKS, P5L12) are
checked. If required, the MP-3000 trips with the appropriate display
message(s). Remaining jogging block times are displayed and
counted down, indicating how long to wait. If there are no such starting
block conditions in effect, the MP-3000 closes (or never opens) the trip
contact and displays READY —3.
9.2.6 Trips and Trip Bypass
If any of the motor protective functions operate while the motor starts
or runs, the MP-3000 opens its trip contact and displays the cause(s)
of the trip. It may also open its trip contact after a stop is recognized if
any jogging function time limit is blocking the next start. In either case,
the MP-3000 expects that the contactor has opened in response and
that no current flows.
If the MP-3000 senses noticeable current for more than about a
second whenever it is tripped, it declares a trip bypass and displays
a message. This means that the relay blocking of the contactor has
been circumvented by the User to start the motor. If the current fails to
stop when the MP-3000 trips a running motor, it may be because of a
User trip bypass or because of a stuck contactor.
MP-3000
Consider the possibility of backup protection for a contactor opening
failure. Configure the AUX1 or AUX2 output relay to pick up for a trip
bypass. Connect the contact to trip an upstream breaker. This pro-
tects the motor from damage in case of a stuck contactor (at the cost
of interrupting other loads connected to the same breaker).
9.2.7 armed/Disarmed Mode
If the MP-3000 is DISARMED (P12L18), trip messages are displayed,
but the trip relay is not operated. This is useful in a critical process, if it
is imperative to keep the motor running while settings are changed or
the relay is replaced. Commission the new relay or settings in the DIS-
ARMED state. Make sure the relay is also set for RUN PGM (P12L6)
before commissioning. Watch for any trip messages and observe the
contents of the thermal bucket for a while. When it is apparent that the
relay behavior is secure and stable, change P12L18 to ARMED.

9.3 aC Line Interruptions

The MP-3000 has an exceptional ability to ride through voltage sags
and interruptions, even longer than a delayed-dropout contactor it
controls. With this capability, most users can avoid the addition of a dc
battery supply or an uninterruptible power supply (UPS).
The MP-3000 relay operates continuously for ac supply voltages down
to 55% of rated value (66 Vac for a 120 Vac supply system; 132 Vac for
a 240 Vac supply).
For a complete supply interruption, the nominal ride-through rating is
13 cycles. The relay typically continues to operate for 13 to 20 power
cycles, depending on power supply loading variables:
• Number of output relays picked up;
• Current being delivered by the 4-20 mA analog transducer
output port;
• Type of PONI communications module powered by the
MP-3000, if any; and
• Electrical URTD communications (using recommended
optical communications lowers this burden slightly).
The one load that may depress the MP-3000 ride-through times below
13 cycles is the use of an Eaton Ethernet PONI (EPONI) for commu-
nications, particularly the EPONI with optical fiber communications. In
this case, ride-through could fall to below 10 cycles. However, this is
easily remedied by powering the EPONI from its own optional external
power transformer. The MP-3000 ride-through then returns to its 13 to
30 cycle range.
In applying this ride-through capability, consider these external factors:
• Typical utility feeder fault tripping and reclosing systems on
overhead medium- or high-voltage feeder lines up to 161
kV cause interruptions of 15 to 20 cycles, especially during
thunderstorms.
• For higher or extra-high voltage supply circuits to large
plants, interruptions may be longer, up to 30 cycles. Deter-
mine if the power system has special mitigating features like
multiple well-separated sources, or local paralleled
generation.
• Conventional motor contactors drop out in 3 to 5 cycles,
stopping the motor.
• Special delayed-dropout contactors that store energy are
available, and ride through interruptions of 15 to 20 cycles.
• Latching contactors or motor breakers may also be used.
They trip only by active unlatching or trip coil energization.
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