Introduction to the Crane
Crane | 14
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 Vertical Motion
The inverter must be selected according to its rated current (I
Drive
) respecting the maximum ambient temperature
specified for each model and altitude of 1000 m (3,300 ft), based on the following criteria:
■
For light or moderate duty operation (installations on maintenance shops, light assembly operations, testing
laboratories, warehouses, pulp and paper industries, etc. where the load requests are on average less than 50%
of rated capacity):
×
×
=
Motor
Load
Motor
Drive
P
P
I
I
15
.
1
■
For heavy or severe duty operation (installations on heavy machine shops, foundries, heavy steel structures
factories, handling steel coils, container handling, timber, storage, scrap, cement factory, sawmills, fertilizer
plants, container handling, etc. Where the loading requests are on average more than 50% of the rated
capacity):
×
×
=
Motor
Load
Motor
Drive
P
P
I
I
30
.
1
Being:
I
Drive
= frequency inverter rated current (A);
I
Motor
= motor rated current considering the service factor (A);
P
Motor
= motor rated power considering the service fact (kW);
P
Load
= power required by the load (kW).
NOTE!
In case of doubt about the duty operation, use the biggest factor (1.30) to determine the current (I
Drive
)
of the CFW500 frequency inverter.
NOTE!
For temperatures higher than the specified as maximum (see table 1.1), limited to 10 °C above, the
oversizing factor (1.15 or 1.30) to determine the heavy duty current (I
HD
) must be increased by 0.02
per °C.
NOTE!
For altitude above 1000 m (3,300 ft) to 4000 m (13,200 ft), oversizing factor (1.15 or 1.30) to
determine the heavy duty current (I
HD
) must be increased by 0.01 to 100 m (330 ft) above 1000 m
(3,300 ft).
NOTE!
For situations where the motor was oversized above the power required by the load, attention should
be paid to the current (I
Drive
) of the CFW500 inverter at least equal to the rated motor current with the
service factor.
Summary of Contents for Crane CFW500 series
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