Solar power to Invertor

[dickieus]

Dan
When talking to the rep I asked about operation costs.
I will post some more pics when I get a chance. The unit I looked at cost about 160K to develop. Considering we operate in california and have to deal with air resouce an all that you have a good case for solar.
P.S. we do Yakima later this year.

 

[dickieus]

Now I am getting into sizing the drive. I need at least a 7.5hp. The situation is that a single phase full wave bridge rectifier produces a lot more ripple than a 3 phase bridge. This means I cannot use a 3 phase inverter without considerably larger capacitors. I am working with several suppliers now. Hitachi seems to be the most helpful.
I still also have to consider the 1/3 (1.732) power to hp loss.

 

[leitmotif]

Now I am getting into sizing the drive. I need at least a 7.5hp. The situation is that a single phase full wave bridge rectifier produces a lot more ripple than a 3 phase bridge. This means I cannot use a 3 phase inverter without considerably larger capacitors. I am working with several suppliers now. Hitachi seems to be the most helpful.
I still also have to consider the 1/3 (1.732) power to hp loss.

Let us define terms first.
Converter changes AC to DC

Inverter changes DC to AC come in varying DC volt (supply) and varying AC output both single phase and 3 phase.

VFD (variable freq drive) is special power supply to drive 3 phase motor at varying speed. Come in 3 "flavors" direct tie to DC supply, single phase and 3 phase supply.

IF you are buying those inverters shown in photos I wonder if they are 3 phase in the first place and if so 208 or 240.
IF SO you can run motor direct off them
UNLESS you need variable speed. In this case get a 3 phase source VFD.

IF inverters NOT 3 phase ie single phase and assume 208 for worst case.
YOu will need a VFD to drive motor.
Your existing one will work BUT you want to replace it.
If you buy one designed to operate from single phase line you do not have to oversize ie 7.5 HP unless you want a bigger unit just for the extra beef / insurance / worst case.

Hitachi would be a good choice I think. AB would be another and probably better supported in small towns. I would venture to say you can find an AB vendor in any town say 50,000 or more.

Dan Bentler
Dan Bentler

 

[dickieus]

Sorry I haven't posted lately. What I went with is a TECO 7300CV 10 HP drive. It seems most modern drives will accept a single phase input. The drive derating of 1/3 is ok but it was recommended that I double the size.
This worked ok but I have a high inertia load and am getting over volt faults. The original syste did not use external braking resistors but i will probably have to add one to this.

 

[leitmotif]

Sorry I haven't posted lately. What I went with is a TECO 7300CV 10 HP drive. It seems most modern drives will accept a single phase input. The drive derating of 1/3 is ok but it was recommended that I double the size.
This worked ok but I have a high inertia load and am getting over volt faults. The original syste did not use external braking resistors but i will probably have to add one to this.

IF it is a high inertia load and you are braking it then you will need braking resistors ASAP to avoid drive damage. Make sure you size them for maximum load and speed on the machine and maybe add 25% just to make sure. You do not need to burn out a resistor(s) 100 miles from spare parts. You may consider letting it coast to stop normally and do the dynamic braking in urgent or emergency situations. Make double sure VFD is water tite not only in place but when doing 60 while in transport - they do NOT like water. Plastic trash bag may be cheap insurance.

The 10 HP drive (I assume 230 VAC 3 phase) may be a good choice especially if you have several 10 HP (or less) 3 phase motors. Otherwise I think you could have gotten 7.5 HP (was it?) in 230 VAC single phase. But commonality is a good thing.

How is the solar portion coming along?
Dan Bentler