DC control system BBC VERITRON Type SZAD

[Johanvdvelde]

Dear Sir,

On the Drilling platform our Draw works is driven by three ABB DC motors, each 750 kW 750 V – 1000 Amps. Each motor is controlled by the armature control system BBC Verithyr SZAD, Type : SZAD 06J1-01 3 x 660 V 1290 Amps.
This system is foreseen of the following control cards :
GU480, GH480, RT480, GT480, XT480, XT481, RT481, IE5A, IE6A, VE6, RE3 and HE11A
Each motor can selected as Master whereby the other two motors are the slaves.
The complete system is very reliable.
During logging I noticed that the current of the “B“ motor
is always higher than the “C” motor, lowest in current is the “A” motor.
Even by selecting the A, B or C as Master is the measurement the same.
These measurement is confirmed with scoop and are taken on the panel meters of the SCR’s namely the Armature Current and Voltage.
These panel meters are giving the correct value compared with the Armature voltage measured with a Fluke and voltage measured over the shunt ( current signal 0-60 mV )
The intension is to make an adjustment on the regulation that the three currents are same and limited to 1000 Amps.
The graph of the logging results see attachment
The question is where and how can I make this kind of adjustment ?
In the hope that someone can help me out with this I stay with sincere greetings.
Johan

 

[shooter]

i would only limit them on 1000 amps, there will always be a difference, if diff below 5% leave it like it is. the motors are different the forces and bearings are different etc.
however it is adjustable by telling the verithyr one motor has more slip for example.

 

[tracer]

Have you checked the brushes & commutator on each motor? and the drive train interfaces? any of the above can create a difference in amp draw. You could also try swapping motors, to see if amp difference follows motor, or stay's the same. Is the Volt/current supplied to each drive the same? there is also a test using an O-scope for each drive, but I don't remember what it is...lol

 

[idbusan]

Dear Sir,
If you don't mind to send us a softcopy / scan for the Manual Book / Wiring Diagram for this veritron drive.
Thank you for your kind support

 

[DickDV]

Johan, since the controller is BBC, that would make it 1988 vintage or earlier. It also is most likely an analog controller.

I am not sure why you are making this request. Is the maintenance burden the same on these motors or does the higher (or lower) current motor need more maintenance? Otherwise, I don't think there is any particular benefit in balancing them.

With the age of the controller, you will be looking at a new digital drive package sometime soon. When you make that change, it will be rather simple to set these motor controllers up as current followers. That way, all of the motors will track current together as you have requested.

I doubt it is practical to do on an analog drive.

 

[salzvo]

Dear Sirs,

We have an old lathe machine (Gildemeister MDW30 from 1980) with spindle drive based on DC converter BBC Veritron (unknown type, there isn't any type plate, see foto). The converter includes following cards: GH480, RT480, GT480, XT480, XT481, RT481 and XS482. Has anybody some documentation for the converter or ideally wiring diagrams of these cards?
Thank you at advance..

Best Regards,

Vojtech – Czech Republic