Star delta issue (driving me insane)

[GSGFaw]

Heeelp!

I have an 11kW/21A motor which is attached to a hydraulic power pack.

I have replaced the old panels with new, using the same star delta starting. When connected to a 415V outlet protected by a C32 breaker, the breaker will periodically trip. This has only manifested since the new panels, but the new control circuit is just a basic star delta (open transition). The only difference is the motor connection on the panel is now pluggable (to allow for quick changeover in the event of a failure).

I've tried "rolling" the connections in the motor (as suggested by an old hand elsewhere) to no effect.

The pump has to be started onload for operational reasons (doesn't trip offload) and this is when the MCB trips; for info, the old starters do not trip the external breaker.

I've checked starting currents using my fluke in max/min and, on average, get around 24A at both the star and delta phases of startup (at the panel's MCCB) and then the running load is 10.7A. When the C32 breaker trips, there is no current spike captures on my Fluke.

If I switch to a D32 fed socket, the issue goes away (obviously), but my guys can't be guaranteed they will have a D type breaker on the site sockets provided.

Anyone dealt with this or have a suggestion as to what I can do to fix the issue? I've wired many star deltas over the decades and never experienced this issue.

p.s. Softstarting not an option as the guys have to inch the motor frequently, and the starts per hour don't even remotely suit one.

 

[GSGFaw]

Thanks for the various suggestions. I eventually had narrowed it down to an issue with the contactors and changed them out for Schneider LC1D type (from ABB AF type) and the issue immediately went away.
After speaking to ABB techinical they said that I was not the first report of this issue and that the AF contactors will only work reliably with their own star delta timer (since they moved to AF range. The old A contactors work fine with any timer). Now my issue is the 2 control supplies available are 415Vac or 12Vdc, neither of which are covered by the ABB timers.
Bizarre, but I canb't argue that the change to Schneider contactors has 100% fixed the issue.

 

[James]

The contactors are available at 400v coil as well

 

[GSGFaw]

View attachment 109051The contactors are available at 400v coil as well

Yeah, I've now got all that but with the electronic timer. The ABB AF contactors aren't compatible with the Schneider SD timer, but ABB don't do a 12Vdc version, so I had to use the Schneider