Hi,
I have my plant with a group of 5 Atlas Copco GA compressors with Dryers embedded (the FF variant) . 
2 x GA200 FF
1 x GA180VSD FF
2 x GA90VSD FF

Since only one to two of the compressors usually are needed, the others are left in standby. However, recently I've noticed that in standby mode, the air dryers are always running. In one of the GA200 the measured average power is 12 kW (strangely is the double of the GA180VSD in standby condition).
The compressors are linked to a central compressor manager, provided by Atlas Copco, but the feedback we have is that the central manager is unable to control the embedded air dryers. 
Recently two of the compressors, that are always in standby were completely shutdown. Is there a better way to do this switch off of the embedded air dryers?
If I install an external air dryer for the whole compressor group, is it possible to switch off the embedded air dryers and do an internal bypass to the air path, in order to avoid the pressure loss in the disabled embedded air dryers?
Many thanks for your help,
Best Regards,
Marcos