Emerson Mentor MP Advanced User's Manual page 63

Parameter Keypad and
structure display
Alternatively the thermal time constant can be calculated from the trip time with a given current from:
Pr 4.15 = -T / ln(1 - (1.05 / Overload)
trip
For example, if the drive should trip after supplying 150% overload for 60 seconds then
Pr 4.15 = -60 / ln(1 - (1.05 / 1.50)
The thermal model temperature accumulator is reset to zero at power-up and accumulates the temperature of the motor whilst the drive remains
powered-up. Each time the rated current defined by Pr 5.07 or Pr 21.07 (depending on the motor selected) is altered, the accumulator is reset to zero.
4.18 Overriding current limit
Bit SP
Coding
Range 0 to TORQUE_PROD_CURRENT_MAX %
Update rate Background write
The current limit applied at any time depends on whether the drive is motoring or regenerating and also on the level of the symmetrical current limit.
Pr 4.18 gives the limit level that applies at any instant.
See Pr 4.16 on page 62.
This parameter displays the current magnitude (Pr 4.01) as a percentage of rated active current. Positive values indicate motoring and negative
values indicate regenerating.
If this parameter is set to one, the drive calculates a torque reference from the motor and load inertia (Pr 3.18) and the rate of change of speed
reference. The torque reference is added to the speed controller output to provide inertia compensation. This can be used in speed or torque control
applications to produce the torque required to accelerate or decelerate the load inertia.
The current demand filter time constant is defined by this parameter if the speed gain select (Pr 3.16) is one.
Mentor MP Advanced User Guide
Issue Number: 1
Parameter description
Parameter x.00
format
2
)
2
) = 89
FI DE Txt VM DP ND
1 1 1
www.controltechniques.com
Advanced parameter
descriptions
RA NC NV PT US RW BU
1 1
Serial comms
Performance
protocol
PS
1
Menu 4
63