Emerson unidrive m200 - Motor Protection Accumulator Warning; Thermal Protection Mode; Drive Thermal Monitoring Current Limiting; Current Limiting on Motor Overload

2. MotorRatedCurrent (05.007) is modified when SelectMotor2Parameters (11.045) = 0, or M2MotorRatedCurrent (21.007) is modified when
SelectMotor2Parameters (11.045) = 1.
Motor Protection Accumulator Warning
If Percentage Losses > 100% then eventually the MotorProtectionAccumulator (04.019) will reach 100% causing the drive to trip or the current limits to
be reduced. If this is the case and MotorProtectionAccumulator (04.019) > 75.00% then a Motor Overload alarm indication is given and
MotorOverloadAlarm (10.017) is set to one.
Parameter 04.016 Thermal Protection Mode
Short description Set to the require thermal protection mode
Mode Open‑loop
Minimum
0
(Display: 00)
Maximum
3
(Display: 11)
Default
0
(Display: 00)
Units
Type 8 Bit User Save Update Rate Background read
Display Format Binary Decimal Places 0
Coding RW
ThermalProtectionMode (04.016) defines the action taken by the drive when MotorProtectionAccumulator (04.019) reaches 100% and/or the drive
thermal monitoring parameters approach their trip levels. The bits in Thermal ThermalProtectionMode (04.016) are defined as follows:
Bit Function
0
0 = MotorTooHot trip is initiated when MotorProtectionAccumulator (04.019) reaches 100%
1 = MotorTooHot trip is disabled and current limiting on motor overload is active as described below
1
0 = Drive thermal monitoring current limiting is disabled
1 = Drive thermal monitoring current limiting is described is active
Because of the limited number of segments on drives with an LED display, these drives will indicate the parameter value as a decimal value rather than
a binary value.
The required current limit is derived from the current limit parameters (MotoringCurrentLimit (04.005) to SymmetricalCurrentLimit (04.007) or 21.027
to 21.029) depending on the set-up and conditions. The current limit can be further limited by current limit on motor overload and/or drive temperature
monitoring as shown below to give the FinalCurrentLimit (04.018).
Current limiting on motor overload
When the MotorProtectionAccumulator (04.019) reaches 100.0% the current limit is limited to (K - 0.05) x 100.0%. This limitation is removed when the
MotorProtectionAccumulator (04.019) falls below 95.0%.
Drive thermal monitoring current limiting
If any of the drive temperature monitoring parameters (StackTemperature (07.004) and AuxiliaryTemperature (07.005)) are above their trip threshold
minus 10°C the one that is closest to its trip threshold is used to modify the current limits as follows:
FinalCurrentLimit (04.018) = Current limit x (Trip threshold - T) / (Trip threshold - 10°C)
where T is the drive temperature monitoring parameter value.
If the PercentageOfDriveThermalTripLevel (07.036) is above 90% then the final 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 frequency and does not include rapid transients (i.e. a fan).
Unidrive M200 Parameter Reference Guide
Issue: 01.05.00.10
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