Current limiting on motor overload
When the Motor Protection Accumulator (04.019) reaches 100.0% the current limit is limited to (K
1
– 0.05) x 100.0%. This limitation is removed when
the Motor Protection Accumulator (04.019) falls below 95.0%. (K
1
is defined in the description of Motor Thermal Time Constant 1 (04.015).)
Drive thermal monitoring current limiting
If Percentage Of Drive Thermal Trip Level (07.036) exceeds 90% the current limit is modified as follows:
Final Current Limit (04.018) = Current limit x (100% - Percentage Of Drive Thermal Trip Level (07.036)) / 10%
If both of the above attempt to reduce the final current limit the lowest calculated value of current limit is used.
This system has the effect of reducing the current limit to zero at the point where the drive should be tripped because its thermal monitoring has
reached a trip threshold. This is intended to limit the load on the drive to prevent it from tripping when supplying a load that increases with speed and
does not include rapid transients.
Parameter 04.017 Magnetising Current
Short description Shows the instantaneous level of magnetising current
Mode Open‑Loop
Minimum −VM_DRIVE_CURRENT Maximum VM_DRIVE_CURRENT
Default Units A
Type 32 Bit Volatile Update Rate 250µs write
Display Format Standard Decimal Places 3
Coding RO, FI, VM, ND, NC, PT
Id, Magnetising Current (04.017) is the instantaneous level of magnetising current scaled so that it represents the r.m.s. level of magnetising current
under steady state conditions.
Parameter 04.018 Final Current Limit
Short description Shows the final current limit that is applied to the torque producing current
Mode Open‑Loop
Minimum −VM_TORQUE_CURRENT Maximum VM_TORQUE_CURRENT
Default Units %
Type 16 Bit Volatile Update Rate 4ms write
Display Format Standard Decimal Places 1
Coding RO, VM, ND, NC, PT
Final Current Limit (04.018) is the current limit level that is applied to give the Final Current Reference (04.004).
Parameter 04.019 Motor Protection Accumulator
Short description Shows the level of the motor protection accumulator
Mode Open‑Loop
Minimum 0.0 Maximum 100.0
Default Units %
Type 16 Bit Power Down Save Update Rate Background write
Display Format Standard Decimal Places 1
Coding RO, ND, NC, PT
See Motor Thermal Time Constant 1 (04.015).
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