We are having an issue where an 120V branch circuit is dropping to 112V during the starting of a motor and causing problems with electronics. This voltage drop is causing several problems and we are searching for answers as to what we are seeing and where to make corrections.
Our system has a...
I have been requested to perfrom an earth resistance test here at our industrial facility. This tested is mandated by MSHA requirements that govern our site.
Our distribution voltage is 4.16kV and our utilization voltage is 480V.
I have been researching this test and plan on performeing a...
I am putting together a design for a VFD controlling two 40hp motors on centrifugal water pumps which are pumping water from a tank.
Only 1 motor ever runs at a time and the other motor is strictly sitting on standby as a backup. The idea is to control the speed of the motor and thus the flow...
The motor that I am referencing is a 350hp 4.16kV induction motor started with a DOL starting method.
The motor came equipped with 6 stator rtds which are connected to a motor protection relay for monitoring. It was discovered recently that one of the rtd's was damaged (failed open) and was...
Is it true that the faster a VFD is ramped during a start then the more current will be drawn by the motor. I have heard this and both seen this in the field. My question now is why?
I'm thinking that for a faster ramp, the faster the VFD changes frequency fast compared to how fast the motor...
I have a siemens MicroMaster 420 VFD. It is a 5hp 480V VFD. Ocasionally the VFD will trip on overvoltage. When looking at the line voltages on the drive we read right around 493V L-L. Should this L-L voltage be enough to drive the DC bus into an overvolatge? I would think this would still...
Hello
I have a 4.16kV-480V Delta/Delta 550kVA isolation transformer used on a 400hp VFD. This transformer is new, and currently the secondary Delta winding is ungrounded. I am debating on weather or not to corner ground this transformer?
The primary of the transfomer is protected with type...
