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5.6 GROUPED ELEMENTS
5
e) MECHANICAL JAM
PATH: SETTINGS
GROUPED ELEMENTS
MECHANICAL JAM
A motor load can become constrained (mechanical jam) during starting or running. The starting current magnitude alone
cannot provide a definitive indication of a mechanical jam; however, the running current magnitude can. The Mechanical
Jam element is specifically designed to operate for running load jams. Starting load jams are detected by monitoring accel-
eration time and speed. The thermal element will also operate during mechanical jams but after a delay when the thermal
capacity reaches 100%. Not only is this ineffective due to the delay but it also implies the maximum waiting time for cooling
before a re-start, which could be restrictive.
This element is armed as long as the motor status is not "Starting"; this includes "Running", "Overload", and "Offline". As
soon as any phase current exceeds the user-selectable threshold, the element picks up and operates after the pro-
grammed time delay. The element uses currents configured under
motor status asserted by the thermal model element. Both the signal source and thermal protection must be configured
properly in order for the mechanical jam protection to operate.
5-164
Figure 5–71: AMP UNBALANCE SCHEME LOGIC
SETTING GROUP 1(6)
MECHANICAL JAM
FUNCTION: Disabled
MECH JAM OVERCURRENT
MESSAGE
PICKUP: 2.00 x FLA
MECH JAM PICKUP
MESSAGE
DELAY: 0.10 s
MECH JAM RESET
MESSAGE
DELAY: 0.00 s
MECH JAM BLOCK:
MESSAGE
Off
MECH JAM TARGET:
MESSAGE
Self-reset
MECH JAM EVENTS:
MESSAGE
Disabled
M60 Motor Protection System
MOTOR
MECHANICAL JAM
Range: Disabled, Enabled
Range: 1.00 to 10.00 x FLA in steps of 0.01
Range: 0.10 to 600.00 s in steps of 0.01
Range: 0.00 to 600.00 s in steps of 0.01
Range: FlexLogic operand
Range: Self-reset, Latched, Disabled
Range: Disabled, Enabled
SYSTEM SETUP
MOTOR
5 SETTINGS
and
MOTOR LINE SOURCE
GE Multilin
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