Frequency Inverter And Braking Resistor Selection Criteria; Horizontal Motion; Vertical Motion - WEG CFW-11 Applications Manual

Introduction to the Crane
■
Temperature: 0 to 50°C, or up to 60°C with 2% / inverter current derating per °C above 50°C;
■
Altitude: 0 to 1000 m, or up to 4000 m with 1% inverter current derating every 100 m above 1000 m.

1.5 FREQUENCY INVERTER AND BRAKING RESISTOR SELECTION CRITERIA

Some criteria have been established for the selection of the frequency inverter and the braking resistor in a
crane application, according to the type of motion to be executed:

1.5.1 Horizontal Motion

The inverter must be selected according to its rated normal duty current (I
Being:
I = Frequency inverter rated normal duty current;
ND
I = Motor rated current.
N
The braking resistor must be selected according to the equation:
Being:
P = Braking resistor power (kW);
R
P = Motor rated power (kW);
M
%ED = Braking duty cycle.
NOTE!
Refer to the CFW-11 user's guide, table 3.3, to verify the ohmic value of the braking resistor to be
used according to the frequency inverter model.

1.5.2 Vertical Motion

The inverter must be selected according to its heavy duty rated current (I
■
For light duty operation in non-aggressive environment:
■
For heavy duty operation in aggressive environment:
Being:
I = Frequency inverter rated heavy duty current;
HD
I = Motor rated current.
N
NOTE!
In case of doubt about the duty cycle and the operation environment, use the biggest factor (1.30) to
select the frequency inverter.
The braking resistor must be selected according to the equation:
=
I I
ND N
= 40 ×
with %ED = 50.0%
P . 0 P
R M
= 15 ×
I . 1
HD
= 30 ×
I . 1
HD
= 70 ×
with %ED = 100.0%
P . 0 P
R M
):
ND
):
HD
I
N
I
N
Crane Horizontal Motion | 12