EPS Interface

We do make use of the two EPS signals provided into and out of the cryopump system.

The cryo Ready output from the cryopump is used by our EPS system to indicate the cryopump is in a good state, cooled down with no faults. When the cryo Ready signal goes away the EPS system assumes a failure of the cryopump and will start closing the gate valves into and out of the kohzu to isolate the monochrometer.

The CC Enable input to the cryopump is fed from the EPS system to indicate that the kohzu mono is under good vacuum and ready to be cooled down. If the CC Enable signal goes away the cryopump will try to protect the kohzu unit by going into Stop mode followed by Stop-Off mode if the condition exists for more than 2 seconds, in stop off mode the cryopump will open up the inner loop and open up the valves needed to vent the sub-cooler and heater vessel and open the N@ purge line.

In order to keep the cryopump in a ready state after a warm up of the monochrometer, a set of loop-back jumpers is provided in the A-hutch EPS rack which jumper-out both cryo Ready and CC Enabled signals. This is only a temporary condition to prevent the EPS system telling the cryopump to go into stop-off mode and thereby warm-up all cryopump componenets. As soon as the monochrometer work is complete and the kohzu is pumped down to operational level these jumpers are removed for normal EPS feedback and control.

Note the EPS control logic depends on other factors internal to the cryopump as show in this diagram https://anl.app.box.com/file/978865258999?s=k4hqj95hc6tsydchsqkprogkx5h6d8dd