Thank you for the analysis, skogsgurra. The drive I was using is a MagneTek GPD205 model CIMR-XCBD21P5. rated for 3hp 0-230Vvac input and 2.7kVA 7A output. max freq 400hz. it was on a 3phase main when the problem occured. I will check the balance of the ac main later then. But the other drive...
I have a 3 hp Dayton induction motor which is rated at 208-230/460V 9.7-9.4A/4.7A at 60hz. 4 pole and sf=1.
when driven with a v-hz type drive with a const v/hz gain 208/60, it behaves strange in the range of 20 to 30hz or so. the three phase currents flickered and the sound from the motor...
Parameters of the motor are not a function of hp, but its intrinsic properties. There are ways to measure/calculate the parameters you mentioned and it involves usage of power meter and running the locked-rotor test, no load test, etc. There is an IEEE procedure described in some thread before...
Did you start the motor with load? Can you try to start the motor with the same drive configuration but don't load it yet, if there is still an overload error, would you double check the winding of the motors and its grounding? also for the drive, i assume it's a v/hz type one, would you double...
how did you configure the battery pack? did you load the motor while it failed? did you measure the battery voltage before, during and after your inverter failed? and by 'fail', is there a failure code given by the inverter?
jraef's answer was clear. the name plate speed is acquired under rated condition. with no load you can pretty much reach 99.9% of the synchrous speed if lube is good. for example if you have a 4 pole machine the synchronous speed is 1800rpm, with no load, you should be able to observe 1799 rpm...
To get a thorough understanding of the load needs more tests. As aolalde pointed out, power factor and efficiency are to be provided.But from my personal experience.. efficiency may not change much within +/-20% full load but power factor may. If it's hard to measure these two quantities in your...
With small slip, load is proportional to square of the voltage and proportional to slip itself. for norminal case: slip =14/1800=0.0077777. Under your case slip=10.5/1800=0.0058333. See if you have the same voltage as rated, 0.0058333/0.007777 = 75%. But when you are running at 4162Volts instead...
Did you put the 2 screws away? It is not terribly difficult to remove the front panel of the drive and you can at lease see if there are more screws stuck in between the boards..
jraef is absolute right in the explanation. One thing I forgot to mention is the load. if the load in your application is always less than your rated W/(100*2pi) N-m, it won't trigger an overload on those advanced drives, which will start the 'field weakening' operation above the base speed(so...
if your motors are rated at 60Hz and you happen to use the V/Hz type drives, you might need to modify some of the parameters on the drives so that the motor would not be operated under much-higher-than-rated voltage for long time. check a so called 'field weakening' operation of the induction...
I would suggest using a digital scope or daq unit instead doing a high-power to logic-power conversion on your own.
some scopes, check if you have some Yokogawa ones, can store quite a lot data (2G and more... ) and some advanced multimeters (fluke.. ) get the interface to the computer... check...
