Y-Delta Start again

[Waxman]

I was at my local motor repair shop Monday getting a door operator capacitor.

While there I asked the owner if he knew how to wire a Y delta start. He said yes but that it required a starter also which cost THOU$ANDS.

Does anyone have such a setup w/starter and if so how much do these cost and what exactly is needed for a 25hp Baldor for my touchfree?

It's an interesting concept, but the payback looks pretty long if I am guessing right.

 

[MEP001]

http://www.claytonengineering.com/t.../WhatTypesReducedVoltageStartersAreThere.html

It doesn't look like it will save you what you want. The primary reason is to reduce the inrush at startup, but you still have that with wye delta. You might be better off with resistor start or a VF drive (The latter can be done without rewiring anything, and they only cost about twice what a normal contactor does).

Have you ever checked with your utility company to see if your bill is based on peak amperage draw? Ours is a flat rate - any changes like this would be a waste of money.

 

[Waxman]

I have N Grid as my power company. I signed up for an energy audit as well as meeting to discuss peak draw and the power available at the pole/my connection because I never felt it was adequate for my wash and detail.

I don't really understand what you mean about the contactor but vfd's are very expensive as I understand it.

 

[MEP001]

A contactor for a 25 HP 3-phase motor costs around $500. A VFD that size is about $1,000. To do wye delta or resistor start, you need at least two contactors, plus a lot of rewiring. A VFD directly replaces a contactor with no other changes.

 

[GoBuckeyes]

Mep, I'm not sure how many amps a 25hp motor draws off the top of my head but I'm sure it's not much more than 80 at 240v. An 80amp contactor with a 110v coil from AutomationDirect is under $100. If you're paying more, you're paying too much.

 

[MEP001]

Mep, I'm not sure how many amps a 25hp motor draws off the top of my head but I'm sure it's not much more than 80 at 240v. An 80amp contactor with a 110v coil from AutomationDirect is under $100. If you're paying more, you're paying too much.

A 25 HP motor can draw as much as 400 amps on start-up. What I've always seen used in equipment is a 3-phase contactor and thermal overload that together costs at least $500. I'm sure you can get a simple 3-phase relay for less, but it won't provide the protection or handle the inrush load.

 

[GoBuckeyes]

A 25 HP motor can draw as much as 400 amps on start-up. What I've always seen used in equipment is a 3-phase contactor and thermal overload that together costs at least $500. I'm sure you can get a simple 3-phase relay for less, but it won't provide the protection or handle the inrush load.

You're correct about the amp draw upon start up, however the FLA for a 25hp 3 phase motor at 220-240v should be around 68 amps. A motor starter and thermal overload is sized by FLA not by the amp draw on start up. If that were the case, your car wash would need a much larger service than you have. Our 5 bay self-serve and two autos only has a 4oo amp 208v service.

This link for AutomationDirect is for an 80 amp Fuji contactor which costs $69. If you add the appropriate thermal overload, you're looking at an additional $45. If you go to this link, there is another link for a motor control selection guide that makes it pretty easy.

Don't get me wrong, if you wanted to spend a $1000 on a motor starter/protector for a 25hp motor it can be easily done. Simply go price an Allen-Bradley or KlocknerMoeller. I have found, howver, that these cheaper alternatives last just as long.

 

[GoBuckeyes]

Oops, I got distracted and forgot to post the link:

http://www.automationdirect.com/adc...ctors_-z-_Overloads/65_to_80_Amp/SC-E4-110VAC

 

[my2cents]

Many utilities will rebate to the customer the cost of a VFD drive. The reason is you are doing your part to conserve energy and they have programs in place to help you get the equipment required to reduce it. I have heard that only on a VFD and not a soft start starter will they give the rebates on and it is dependent on the individual utility. its worth the investigation.

 

[dreese]

A quality VFD sized for a 208/220VAC, 3Ph, 25HP motor should run you around $2,200 - $2,400. A soft starter sized the same would be around $1300. Check with your local utility regarding rebates and if/how they handle them.

 

[RykoPro]

Another drawback to touchless........nothing larger than a 1 horse motor on a Softgloss.......

 

[sparkey]

If you switch to a VFD they should be installed with a line reactor in front of the incoming 3 phase. Variable frequency drives are electrically very noisy and will if a line reactor is not used will put harmonics back onto your incoming 3 phase power. It is also recommended that a load reactor be placed after the drive if the distance between the drive and motor is a long distance. The load reactor probably won't be an issue though at a car wash because the cable lenght will problaly be less than a hundred feet.

If you use a VFD you should also use an inverter duty motor. Inverter duty motors have better insulation on the wires and can handle the changing frequency of the drive. A normal duty motor will work on a VFD but it will have a reduced life span.