Overhead travelling cranes ［Hoisting equipment］ |
 Notices regarding the use of inverter drives
- Overload trips by frequent inching operation
Frequent inching operations may cause overload trips.
When you use many inching operations within a short time, please monitor the inverter display to avoid inverter overload.
- Surge voltage of magnet contactors
Operations of magnet contactors cause surge voltage.
Therefore, please install surge reduction filters for magnet contactors.
- Contact loss of trolley wire
When overhead travelling cranes use trolley wires between inverters and motors,
contact loss of trolley wires will cause inverter trips.
In this case, please replace trolley wires with cab-tire cables.
- Brake operation
VF-S15 and VF-AS1 has a special function for brake operation.
Using this brake function, inverters can control mechanical brakes with output torque dectection for added safety.
However, please adjust this function with an initial load test to assure it works reliably.
- Low speed operation
Generally motors need to reduce their output torque when operating under 30Hz.
The motors are cooled by fans mounted on their shafts, so when the motor speed decreases, the cooling efficiency also decreases.
Special motors for inverter drives don't need to reduce their output torque between 6 to 60Hz.
- Electromagnetic noise
The inverter is generating "electromagnetic noise".
If there are some high accuracy sensors or other sensitive equipment near the inverter drive,
the inverter's noise may cause some trouble or a malfunction.
Electromagnetic noise can be avoided by installing an external noise filter or
using a different wiring method.
- Harmonics
The inverter is generating "harmonics".
These harmonics sometimes cause a malfunction in other control equipment
that is connected to the same power source.
Harmonics can be avoided by installing an external "reactor".
To decrease "harmonics", we recommend to install DC reactors in all our inverter models.
(NOTE: 100V input models require AC reactors.)
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