5–62
MM300 MOTOR MANAGEMENT SYSTEM – INSTRUCTION MANUAL
CONTROL ELEMENTS
CHAPTER 5: SETPOINTS
Undervoltage autorestart
The undervoltage restart element (UVR) provides for relay initiated undervoltage motor
restart after a momentary power loss (dip). In addition, this element provides for controlling
the timing of both controlled starts and undervoltage restarts following interruptions.
When the auxiliary voltage supply drops below the dropout voltage level, the motor
contactor(s) are de-energized until the dip is over as indicated by supply recovery to the
pickup level. The duration of the dip is classified as short, medium, or long, based on
settable time thresholds.
•
Short dips are intended to cover situations where it is appropriate to immediately
close the contactors back in on voltage recovery.
•
Medium dips are for where it is appropriate to restart the motor with any staged
startup sequence the starter type might provide.
•
Long dips (interruptions actually) are intended to cover cases where restoration is
from backup power, and there must be substantial intervals between starting different
motors to maintain stability, and/or only critical motors can be started.
If the motor was running at the time a short dip occurred, a forced restart will occur as
soon as the relay detects healthy auxiliary voltage. An immediate restart bypasses any
pre-contactor and staged startup sequence the starter type might otherwise provide.
If the motor was running at the time a medium or long dip occurred, after a settable
medium or long delay, a normal start will be performed.
If the motor was not running at the start of the dip, no restart sequence will be initiated.
Start controls are ignored while the UVR delay is timing out. While the UVR timer is
counting down, the status will change to "UVR Pending". During UVR Pending, any stop or
trip will immediately cancel the restart sequence.
With control voltage derived from the incoming motor supply, the MM300 will experience
the same interruption as the motor. The MM300 is designed to ride through power outages
of up to 500 ms, so that the undervoltage restart function is accurate. For longer outages
the relay saves critical data to non-volatile memory just before shutting down. While the
relay is shut down, a backup timer continues to keep time without external power by using
stored energy.
Figure 5-36: Undervoltage autorestart screen
The following setpoints are available:
[Path: Home > Setpoints > Control > UV restart]
Under Voltage Restart
Range: Enabled, Disabled
Default: Disabled
This setpoint enables the undervoltage autorestart function.
Summary of Contents for Multilin MM300
Page 20: ...1 14 MM300 MOTOR MANAGEMENT SYSTEM INSTRUCTION MANUAL SPECIFICATIONS CHAPTER 1 INTRODUCTION ...
Page 184: ...6 8 MM300 MOTOR MANAGEMENT SYSTEM INSTRUCTION MANUAL COMMANDS CHAPTER 6 DIAGNOSTICS ...
Page 198: ...A 6 MM300 MOTOR MANAGEMENT SYSTEM INSTRUCTION MANUAL REPAIRS CHAPTER A APPENDIX A ...