View Full Version : Where can I buy a star delta resistor module ( for closed transition starting)

17-05-2012, 01:42 PM
Am looking to replace a knackered resistor module ( utilized in a S/D closed transition starter) serving a Bitzer compressor as the existing one , having failed previously , is not up to the task as its sited external to the control panel in an IP13 enclosure.
Want to install in control panel with a physically smaller one if possible ( as existing type is rather large to say the least).
The Compressor is a Bitzer CSH 9561 160
Starting current; 436A
FLA; 280A

Please advise if possible.
Thanks in advance

17-05-2012, 08:31 PM
Hi Brazer.
Am I missing something?

Only having checked the latest Bitzer tech document for your screw comp.

The only reference I can find relating to a "Resistor", is the use of capacitors for the provision of Power Factor correction.
With the sizing and use of these being very specific.

Check out this document via the below link.


18-05-2012, 03:15 PM
we have a few of these beasts none use transition resistors.
if you have them fitted via a contactor like in the trane units starter panels, you can cancel the use of them .
i would reccomend the use of a soft starter.
good luck

18-05-2012, 10:30 PM
It sounds like the resistors may have been added to the star/wye configuration to reduce inrush, I have seen this done before on similiar sized motors. Where the feeders and switch gear has been installed on a tight budget almost causing instantaneously trip the o/l on start up without the addition of resistors. The only thing is though the high wattage resistors eventually burn out if their not adequatley ventilated. Maybe you need to look at adding a transformer to reduce the voltage and proportionallly reduce the inrush through the star contactor, or a stepped up resistor network switched in by a multi channel timer if you can't source that sized resistor. Or like goshen says, install a soft starter. Depends on the repair budget I suppose. The only thing wrong with soft starters is when they fail they are practically disposable due to being sealed. At least if you stay with traditional starting methods individual components can be replaced when they fail, making your next repair more competetive.

Have you tried RS or Farnells?

20-05-2012, 04:11 PM
usually these resistors are added to absorb the current jump when changing from star to delta.
inline resistors as chiliwilly suggests are big mama's, and should be as he said either air cooled or oil cooled.
the new soft starters are cheap and very easy to change .the digital ones, actully stop the motor before major damage occures ,thus actully saving money!!
good luck

21-05-2012, 01:59 AM
Are you talking about autotransformers, they are old hat these days, convert to a soft starter as per Goshen's post. the take up minimal amount of panel space, easy to set-up.