Staging TT300 at high pressure ratio

[wusel]

Hi everybody and greetings from Germany,

we have worked on process cooling units with Danfoss Turbocor TT300 for quite a while. As most of our applications are air-cooled condensers we are operating at high-pressure ratios in summer. We have problems bringing a second or third TT300 in whilst one is already running. Before I provide more details I want to ask if anyone has experience with this szenario and how to solve problems with "Front Radial Bearing Fault".

Thanks for any comments in advance!

Markus

[KosmisB]

Hi markus,
did you re-calibrated the bearings, and check the Amps off the bearings. frontbearing for TT300 pin 1-2 (2,75ohm - 3,00ohm) pin 3-4 (2,75 ohm - 3,00 ohm) if this not helps then check the BMCC and/or the PWM modul.

[coolMCX]

Hi Marcus,
Staging at high pressureratios is not allowed. You need to respect a maximum pressure ratio of 2.1 before starting additional compressors.

[Bash1803]

I don't know how much this helps, but we use electronic gate valves on the discharge line, with a bypass line back to the compressor suction which allows the starting compressor to build up a pressure ratio before opening it to the discharge line, and the rest of the system.