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AllenWest DC crane control


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#1 OFFLINE   DeanB

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Posted 27 November 2013 - 10:25 AM

Hi guys, wondering if anyone has come across a situation where a differential relay is connected across the incoming DC supply to a crane which is then controlling a contactor pulling in whats labelled as "BALLAST" resistors? they dont appear on any drawings available for the crane and AllenWest dont have any info on the installation itself so cant help. The fuses have been pulled so it is not in circuit.

 

The reason I ask is that we have just fitted a DC to AC inverter but this blew up due to regen from the system of up to 1100V. Is this device related?

 

Photo of the offending item is attached.

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#2 OFFLINE   RBURNS Re: AllenWest DC crane control

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Posted 27 November 2013 - 10:47 AM

Out of my area, but there is this thread that contains some allen west control information that may be of help.


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#3 OFFLINE   Tony Re: AllenWest DC crane control

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Posted 27 November 2013 - 01:22 PM

The resistors are for regenerative reverse voltage limiting. Lowering a load the hoist motor is generating, without the resistors you have no voltage control. The fuses must be reinstated.

 

The system I worked on had two cranes on the same supply. If one crane was generating the other would absorb the current. If both were lowering then the regenerative power was adsorbed in to the general plant. The main switch board had 150KW loading resistors to dissipate the unwanted power, switched in by a reverse power relay.

 

To be honest an inverter on a crane system isn’t going to fair well. As you’ve found the voltage is unstable. I’m sorry but it’s the nature of the beast.

 

Allen West are very helpful, but they only have drawings going back 15 years.


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#4 OFFLINE   Tony Re: AllenWest DC crane control

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Posted 27 November 2013 - 01:27 PM

I don’t know if this would work, a reverse bias diode fitted to the resistors may control the voltage better. It’s one of them you just have to try.


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