Page 98 I.L. 17562
PR 0.3 Effective 8/99
see 9.2.2 just above. 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)
• 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 2% of rated
ct secondary current on all three phases (0.1 A for 5 A Cts). Then, a stop is declared. Jogging
limits, as listed in 9.2.2 above plus antibackspin time delay (ABKS, P5L12) are checked and if
required, the MP-3000 trips with the appropriate display message(s). Remaining jogging block
times are displayed and counted down, telling the user 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 is then open in response
and that no current flows.
If the MP-3000 sees noticeable current for more than about a second whenever it is tripped, it
declares a trip bypass and a message is displayed. 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.
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 will protect 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 will not be operated. This is useful in a critical process, if it is
imperative to keep the motor running while setpoints are changed or the relay is replaced.
Commission the new relay or settings in the DISARMED 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 uninterruptable power
supply (UPS).
The relay will operate 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).
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