DM61850
Electrical
- Sep 9, 2019
- 80
There are 4 types of transfer in the M-4272.
You have:
Fast Transfer - if you are synced your loads will be switched to the new source if under the time limit
In phase- the relay will attempt if it can a synced transfer when the motor voltage and new source voltage are near in synced
Residual voltage transfer happens after the loads bus voltage falls below a certain value. 20-25% pu v
Fixed time - transfer happens after a fixed period of time. This gives the motors a chance to come to a stop before being restarted
The problem I am having is that the job got handed to me when someone quit. The impression I was given was that we would use another customer's fast transfer, in phase, and residual settings as a go-by. I don't have any motor information or anything. I see that ANSI C50.54 wants you to keep the V/Hz of the motors below 1.33 but I have no way of calculating this without knowing how the voltage and frequency will decay.
It would be nice to be able to put something really conservative in for the sync parameters and windows until a further review can be done. In reading, it sounds like a lot of transfer schemes don't even have sync check. Am I being too conservative? Are there some rules of thumb I can use? I don't want to but I am kind of tempted to just disable fast and In phase transfer until a further review is done. I don't any equipment damaged and I am afraid that if I enable fast and inphase we would look bad if something happened even if the customer was ok with best guess until a study was carried out.
Are there any rules of thumb I can use so that the customer has something or should I just disable fast and In phase until someone does a study? Am I being too conservative?
You have:
Fast Transfer - if you are synced your loads will be switched to the new source if under the time limit
In phase- the relay will attempt if it can a synced transfer when the motor voltage and new source voltage are near in synced
Residual voltage transfer happens after the loads bus voltage falls below a certain value. 20-25% pu v
Fixed time - transfer happens after a fixed period of time. This gives the motors a chance to come to a stop before being restarted
The problem I am having is that the job got handed to me when someone quit. The impression I was given was that we would use another customer's fast transfer, in phase, and residual settings as a go-by. I don't have any motor information or anything. I see that ANSI C50.54 wants you to keep the V/Hz of the motors below 1.33 but I have no way of calculating this without knowing how the voltage and frequency will decay.
It would be nice to be able to put something really conservative in for the sync parameters and windows until a further review can be done. In reading, it sounds like a lot of transfer schemes don't even have sync check. Am I being too conservative? Are there some rules of thumb I can use? I don't want to but I am kind of tempted to just disable fast and In phase transfer until a further review is done. I don't any equipment damaged and I am afraid that if I enable fast and inphase we would look bad if something happened even if the customer was ok with best guess until a study was carried out.
Are there any rules of thumb I can use so that the customer has something or should I just disable fast and In phase until someone does a study? Am I being too conservative?
