Motor Start Supervision - GE M60 Instruction Manual

CHAPTER 5: SETTINGS

5.8.7 Motor start supervision

5.8.7.1 Menu
SETTINGS  CONTROL ELEMENTS  START SUPERVISION
 START SUPERVISION

The motor start supervision feature consists of three elements that guard against excessive starting duty. These elements
are in addition to the start inhibit that can be imposed by the thermal model. A method to prevent starting is by wiring an
M60 output contact actuated by motor start supervision elements in the motor energizing control circuit. The output
contact changes state only when the motor is stopped to accommodate control circuits that must be continuously
energized, such as a contactor.
The three elements of motor start supervision are
• Maximum starting rate (starts per hour) — This element defines the number of start attempts allowed in a
programmable time interval. Only the number of restart attempts during the interval is controlled and not the time
between. The latter is controlled by the time between starts element. When the motor is stopped after the last allowed
start, the energizing or closing control circuit is disabled until the end of the defined interval. Every start initiates a new
interval in which the start number is limited. A typical starting frequency is three starts per hour.
• Time between starts — This function enforces a programmable minimum time duration between two successive start
attempts. A time delay is initiated with every start, and if the motor is stopped a restart is not allowed until the
specified interval has lapsed.
• Restart delay — The restart delay function defines a programmable delay after a motor has stopped before it can be
started again. It allows load interruption transient conditions, such as down-hole pump applications where
gravitational force causes reverse rotation to subside. Starting when the load is reversing can cause damage to the
motor or pump.
5.8.7.2 Maximum starting rate
SETTINGS  CONTROL ELEMENTS  START SUPERVISION  MAXIMUM STARTING RATE
 MAXIMUM STARTING
 RATE (STARTS/HR)
The element can be programmed to perform the classical monitoring function of Starts Per Hour. However, time interval
units specified by the
START/HR TIME INTERVAL
setting specifies the start attempt number limit during the interval. The time unit and ranges accommodate the
STARTS
starting requirements of large direct-on-line motors.
The element asserts the following three FlexLogic operands:
M60 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
 MAXIMUM STARTING

 RATE (STARTS/HR)
 TIME BETWEEN

 STARTS
 RESTART DELAY


STARTS/HR FUNCTION:

Disabled
STARTS/HR TIME

INTERVAL: 60 min
STARTS/HR MAX NUMBER

OF STARTS: 3
STARTS/HR BLOCK:

Off
STARTS/HR TARGET:

Self-Reset
STARTS/HR EVENTS:

Disabled
setting are in minutes for increased flexibility. The
See below
See page 5-242
See page 5-243
Range: Disabled, Enabled
Range: 1 to 300 minutes in steps of 1
Range: 1 to 16 in steps of 1
Range: FlexLogic operand
Range: Self-Reset, Latched, Disabled
Range: Disabled, Enabled
STARTS/HR MAX NUMBER OF
CONTROL ELEMENTS
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