We’re in the process of reviving a LakeShore Model 622 operated in parallel with a Model 612. The units have not been running since 1997, but have been stored appropriately. We’re running the system in local mode (input via display). We would like to assure ourselves that the two units operate correctly before connecting it to our SC magnet. We have the manual and believe we’re following the given instructions accurately.
However, when testing with a low set current (5 A) we notice that the Model 622 unit delivers all the current, while the Model 612 supplies 0 A. Thus, the load isn’t shared between the PSUs as predicted in the manual.
We have connected the Model 2001 cards with a short (0.5 m) RJ11 cable. The dip switches are set as follows (Model 622: 1 on, 4 on, 2, 3, 5 through 8 off; Model 612: 2 on, 4 on, 1, 3, 5 through 8 off). The Mode switches are set as follows (Model 622: I and V on; Model 612: I on, V we’ve tried both on and off as the manual gives contradictory information). We’ve connected the RI and FLT signals, as well as the OVP, as specified by the manual. We power up the Model 622 before the Model 612.
We have indications that the two units communicate to some extent as we get an error message when the Model 612 unit is switched off.
So, can you spot some error in our approach, or is it normal that only the Model 622 provides all the current for so low set values? Can we go ahead to our nominal set current (200 A) on a dummy load?
Post by Lake Shore Jeff M on Jan 28, 2019 12:52:35 GMT -5
The two power supplies you have were manufacture discontinued more than 15 years ago so we can only provide limited support as we have no one at Lake Shore that has ever used these supplies. Are you using the 601 control unit or just the two supplies? With the 601 control unit installed we believe the current should be shared, however, we are not sure how it operates without that unit.
Looking at the User Manual it looks like you have everything configured correctly so I would recommend increasing the current by 15 to 20 Amps and seeing if the supplies start sharing the load. If they do not share the load, you could try going to 130A and seeing if the second supply comes on once the 622 reaches its 125A maximum output.
Thanks for your swift response. No, we aren't using a separate 601 control unit, but this is part of Model 622. Since last time we've been trying to go above 130 A, but it stops at 125 A. We're investigating if we have some communication issues and will get back to you when we have some news.