Emerson Powerdrive F300 Reference Manual page 64

If Rated Core Loss (04.046) ≤ No-load Core Loss (04.045) then only the no load value is used and PCoreLoss = No-load Core Loss (04.045). This
provides some compensation for core losses, but not the load dependent component. The core loss power values can be difficult to obtain except by
experimental measurement because the loss mechanisms within the motor are complex and are affected by the PWM frequencies applied to the motor
by the drive. It is possible to obtain an estimate for No-load Core Loss (04.045) during auto-tuning for RFC-A mode, but not RFC-S mode. As the auto-
tuning algorithm cannot measure Rated Core Loss (04.046) this is set to zero, so that it is not used. If power dependent core losses are to be included
Rated Core Loss (04.046) must be set by the user.
Parameter 04.027 Low Load Detection Level
Short description Defines the low load detection level
Mode Open‑Loop
Minimum 0.0
Default 0.0
Type 16 Bit User Save
Display Format Standard
Coding RW
If Low Load Detection Level (04.027) is set to 0.0 the low load detection system is disabled, otherwise the low load detection system is enabled. The
low load detection system is provided so that loss of load can be detected and action taken. So that the detector can be used with fan and pump type
loads, where the load is relatively light at low motor speed, the detector is only active when the output frequency or speed is above the level defined
by Low Load Detection Speed/Frequency Threshold (04.028). The detector is also only enabled when the motor is at the required speed (i.e. not
accelerating or decelerating), and so it is only active when At Speed (10.006) = 1. Once the detector is active, the low load condition is detected when
the Percentage Load (04.020) falls below the threshold defined by Low Load Detection Level (04.027). Therefore the condition for detecting low load is
given by,
At Speed (10.006) = 1 AND |Output Frequency (05.001)| > Low Load Detection Speed/Frequency Threshold (04.028) AND |Percentage Load
(04.020)| Low Load Detection Level (04.027)
The diagram below shows a typical fan type load and the shaded areas define where low load is detected.
Enable Trip On Low Load (04.029) defines the action taken when low load is detected. If Enable Trip On Low Load (04.029) = 0 a Low Load warning is
displayed and Low Load Detected Alarm (10.062) is set to one. If Enable Trip On Low Load (04.029) = 1 no warning is given, but a Low Load trip is
initiated.
Parameter 04.028 Low Load Detection Speed/Frequency Threshold
Short description Defines the low load detection speed/frequency threshold
Mode Open‑Loop
Minimum −VM_SPEED_FREQ_REF_UNIPOLAR Maximum
Default 0.0
Type 32 Bit User Save
Display Format Standard
Coding RW, VM
See Low Load Detection Level (04.027).
64
Maximum 100.0
Units %
Update Rate Background read
Decimal Places 1
VM_SPEED_FREQ_REF_UNIPOLAR
Units
Update Rate Background read
Decimal Places 1
Powerdrive F300 Parameter Reference Guide
Issue: 01.15.00