I've always used either trip relays or the VFD thermistor inputs for this purpose, so I cannot verify that a PLC input will work. It does look quite possible though. A PLC voltage input card should have a very high impedance (in the megaohm range), so it shouldn't have any unwanted loading...
Hand should always go to the starter or device you are controlling, never directly to the PLC. This was if the PLC crashes, you can still run your process manually. All that's needed at the PLC is your Auto signal.
Choose a panel with a high MTBF. You'll pay more for it, but it's less likely to quit on you when you need it most. Brands such as PanelView and Magelis hold up really well in tough environments. I would stay away from the Automation Direct stuff in your application.
jraef,
This I know. Little back story...
This 25kv service and 250hp pump was installed for the farmer about 20 years ago for crop irrigation. Well about 4 year ago, one of the overhead distribution poles rotted and snapped off which is typical for pine poles, hence the mandate to only use...
waross,
I wish I could, but this is a very simple soft starter. It's a Siemens SIKOSTART 3RW34 which only has a voltage limit and ramp time. There is no direct current limiting settings. I'm just looking for some confirmation that 2.5% drop on the 25kV line seems reasonable.
Source voltage is 25kv, and goes through a 25k/600 WYE transformer with 6.3% Z then to motor starter. I gave you source impedance for the utility demarcation location which is where we need to check voltage drop. Impedances are in ohms, yes.
magoo2,
Luckily I do have the source impedances and have used those in the simulation. R1=4.71, X1=17.29, Symmetrical Fault Current = 800 amps. I am getting about 2.5% voltage drop at the source which means there will be restriction on when this motor can start. I'm just not confident in this...
I was recently asked to do a motor starting study by the local utility for a 250hp vertical turbine pump. They are worried that the line voltage may sag more than 2% on startup, and if so, they may place restriction on time of day that it can be run. Now, I know enough in ETAP to be dangerous...
Hello,
I just created a star coordination in ETAP, but it seems that all displayed values are being transformed through my transformer turns ratio.
The simulation is very simple: 25kv overhead electrical service into a 25kv/600v 1000kVA transformer with primary fusing. On the secondary there...
Thanks for the info. I ended up going with 4/0 for the run. By my calculations, it should be under 5% voltage drop which will be a little nicer on the motor...
Never done this before as I am an electronics guy. Need to size an Aluminum conductor to feed a 3ph induction motor that is 550 meters (1800 feet) away. Motor is 600v and faceplate current says 85 amps. Power factor 80%. Allowed 5% voltage drop on the line. What size of conductor do I...
