Powerdrive F300 Getting Started Guide 97
Issue Number: 5
Safety
information
Product
information
Mechanical
installation
Electrical
installation
Getting started
Basic parameters
(Menu 0)
Running the
motor
Optimization
NV Media Card
Operation
Further
information
UL listing
information
Where:
T = Motor Protection Accumulator (04.019)
K
2
= Motor Thermal Time Constant 2 Scaling (04.038) / 100 %
τ1
= Motor Thermal Time Constant 1 (04.015)
τ2
= Motor Thermal Time Constant 2 (04.037)
K
1
= Varies, see below
If Pr 04.025 is 0 the characteristic is for a motor which can operate at rated current over the whole
speed range. Induction motors with this type of characteristic normally have forced cooling. If
Pr 04.025 is 1 the characteristic is intended for motors where the cooling effect of motor fan reduces
with reduced motor speed below 50 % of base speed/ frequency. The maximum value for K1 is 1.05,
so that above the knee of the characteristics the motor can operate continuously up to 105 % current.
Figure 8-1 Motor thermal protection (Normal Duty)
Both settings of Pr 04.025 are intended for motors where the cooling effect of the motor fan reduces
with reduced motor speed, but with different speeds below which the cooling effect is reduced. If
Pr 04.025 is 0 the characteristic is intended for motors where the cooling effect reduces with motor
speed below 15 % of base speed/frequency. If Pr 04.025 is 1 the characteristic is intended for motors
where the cooling effect reduces with motor speed below 50 % of base speed/frequency. The
maximum value for K1 is 1.01, so that above the knee of the characteristics the motor can operate
continuously up to 101 % current.
When the estimated temperature in Pr 04.019 reaches 100 % the drive takes some action depending
on the setting of Pr 04.016. If Pr 04.016 is 0, the drive trips when Pr 04.019 reaches 100 %. If
Pr 04.016 is 1, the current limit is reduced to (K - 0.05) x 100 % when Pr 04.019 reaches 100 %.
The current limit is set back to the user defined level when Pr 04.019 falls below 95 %. The thermal
model temperature accumulator is reset to zero at power-up and accumulates the temperature of the
motor while them drive remains powered-up. If the rated current defined by Pr 05.007 is altered, the
accumulator is reset to zero.
The default setting of the thermal time constant (Pr 04.015) is 89 s which is equivalent to an overload
of 150 % for 60 s from cold.
0.00
0.70
1.00
Pr = 0
Pr = 1
04.025
04.025
1.00
1.01
Base speed/
frequency
50% of
base speed/
frequency
15% of
base speed/
frequency
K
Powerdrive F300 Getting Started Guide English Iss2.book Page 97 Tuesday, July 28, 2015 3:23 PM
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