Motor Protection Accumulator Warning; Thermal Protection Mode; Drive Thermal Monitoring Current Limiting; Current Limiting On Motor Overload - Emerson Unidrive M200 Parameter Reference Manual

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
0
Minimum
(Display: 00)
0
Default
(Display: 00)
Type 8 Bit User Save
Display Format Binary
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 = Motor Too Hot trip is initiated when Motor Protection Accumulator (04.019) reaches 100%
0
1 = Motor Too Hot trip is disabled and current limiting on motor overload is active as described below
0 = Drive thermal monitoring current limiting is disabled
1
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
3
Maximum
(Display: 11)
Units
Update Rate Background read
Decimal Places 0
59