Incoming Power to my Carwash

I got a odd question for you guys. I have 3 phase service and currently getting 211 volts to all my equipment and electrical panels from the street. I did amp draws on all my motors and there a little high amperage and there’s no telling how many years this has been like this. All my motors are rated at 230 volts not 208 my power company’s says they came out this morning and checked there stuff and said it’s correct and there no room for them to adjust it to 230 volts. Is this correct I just want to make sure there not to lazy to change the transformer at the street or jerking me around. Thanks Thomas

Usually from what I see, if a motor is rated for lets say 230v that would typically mean the max voltage. 208 volt systems will work no problem with motors with 230v rating. once you step up into the 240v range then you will probably have to consider other options such as buck boost transformer or something of that nature.

I've had the opposite issue when doing new construction. We would install Belanger automatics equipment which called for 208 voltage but sometimes the city didn't want to pay to put up a third transformer. Your power may be different, here there's either two transformers on the pole giving 120/120/277 and 240V 3 phase or three transformers giving 120/120/120 and 208V 3 phase. It took a lot of arguing to get 208 in and we were successful every time but one, where we ended up installing a transformer the size of a washing machine in the room.

I just looked up at our pole & it has 3 transformers & a wild leg thingy with its 240VAC 3 phase. I tend to measure over 240VAC & the amp draw is consistently the same on each of the the 3 wires to all my 3 phase motors. I was told that Delta Wild Leg is very common across the country even though if you have a lot of 120VAC internal whatever in the facility ... balancing the total individual circuit breakers complicates the main panel a bit. Our local utility based on experience tends to leave a monitoring device interfacing with the outdoor meter for at least a day ... if there is any suspicion whatsoever of a problem with their distribution.

How are you checking voltage? Each leg to ground? Or across two phases? My guess is you have the wild leg three phase like I have. Checking each leg to ground you have 120v,208v,120v. Checking across any two legs gives you 240v. The cycle timing of the 208v leg is such you get 240v when checking either of the 120v legs with the 208v leg. You have to google search "Wild Leg 3 Phase" to see what I am talking about.

I have 3 phases that comes from the street transformer and splits off at the mast to (2) separate meters and then to (2) separate panels. One panel is 3 phase 240v and the other panel is single phase 240v all fed from the 3 wires coming from the street transformer.

The system was developed years ago to supply businesses with 3 phase, single phase, and also a high voltage leg to run 208v lighting circuits. You ever take apart the old mercury vapor light fixtures and notice there was a 208v tap on the transformer? Hardly anyone uses the 208v leg by itself any more, but this type of 3 phase still works for setups like a carwash.

My power is delivered by our city. They own the utility and supply 208 to most businesses. One thing to look at is any small transformer within your wash that supplies power to solenoids, coin techs etc. Most transformers are setup to convert 240 to 24 volt but if supplied with 208 you get around 22 volts and that Will cause problems. Be sure you have 24 + volts out of your transformers.

unless your motors are fully loaded (carwash motors are typically not fully loaded) 208 will work fine. You get less horsepower but the pumps don't know the difference because they will turn the same rpm. The motors will use a little less power with lower voltage.

wash4me said:

unless your motors are fully loaded (carwash motors are typically not fully loaded) 208 will work fine. You get less horsepower but the pumps don't know the difference because they will turn the same rpm. The motors will use a little less power with lower voltage.

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Pretty much right, except that you wont get less horsepower... The amperage would increase by the same proportion that the voltage is decreased. Example: [(240-208)/240 = 7.5% less voltage. So amperage would be 7.5% higher. This doesn't make any problem until the amperage exceeds the nameplate rating. Then you start getting into the service factor. If you exceed the service factor (typically 10%) then you will start to overheat the motor and cause early failures. I would check the current at each of these motors and see if the amp draw is less than the nameplate. If it is, drink a beer. If it is much more... drink several more beers.

Running 208v on a 230v motor is fine usually but you get a higher amp draw. It’s also a good idea to do an amp test annually. If you notice it creeping up it’s a sign the motor is going (doesn’t mean it will die immediately but is toward end of life)

The horsepower of the motor is lowered when voltage is lowered. Since the car wash pumps rarely use the full horsepower of the motor it becomes irrelevant. For example if a 5 hp motor would put out 5 hp at 240 V and if you were to try to get the 5 hp out of it at 200 V it would overheat from higher amps and and decrease its service life. If you study the charts in the pump information it will tell you at a particular pressure and RPM what horsepower is required. If it were me and the motors are replaced I would replace them with a 208-230 volt motors Because they are rated to run the full hp at 208 volts. I am not saying you need to replace the motors just if one burns up replace it with a 208-230 volt motor

3-phase motors are usually rated to run +/- 10% voltage. Running a 230v motor on 208V is within that 10%, so no harm will come to the motor, and you don't need to limit the horsepower use to prevent overheating.

I'm thoroughly phased!!

Thanks for all the replies guys. The power company said that everything on my side of town is 212-214 volts and it’s nothing I could do really. Even though if I had true 230-240 I would draw less amps for sure

It shouldn't be a problem. I've only seen issues with VFD systems that needed a more accurate voltage, and with 240 to 24 volt transformers running 208 and having an extremely long wire run. Voltage drop was too much, and even that was fixed by doubling up the power and motor starter wires with spares.