FCBN taps

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mb5412

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Hello, we have treadmills in our fitness center that's rated for 240v, single phase.
We've been getting complaints of the treadmill motors overheating.
The branch circuit panel is less than 50' away. The tech that services the treadmill says the minimum operating voltage needed is 210v.
Our building supply is 208/120v.

My question: Can the branch circuit panel transformer's primary side Full Capacity Above Normal taps be adjusted to boost secondary voltage?
If so, will this affect transformer operation or trip its feeder circuit breaker should the utility's supply voltage fluctuate?
ie: present voltage @ substation secondary - 500vac, this is normally 480vac.
Hope my explanation makes sense.

Thanks in advance - LB
 
Re: FCBN taps

Your explanation makes perfect sense.

Changing your taps is not a great option as it will boost your 120 along with your 208.

Add that boost to the utility's hitting 500 volts and you will have to high a voltage on every device connected to that transformer.

IMO a better way to go would be buck/boost transformers for each of the treadmills.

If you pick the correct buck/boost you can get 236 volts from the 208 supply.

Another route, if there is a lot of tread mills is a 480 to 240/120 transformer with a separate panel.
 
Re: FCBN taps

It is common for transformers to have primary taps to compensate for high or low primary voltages. I would look for (2) 2-1/2% FCAN taps and (4)2-1/2% FCBN taps. The above normal taps would allow you to configure the transformer that has a high primary voltage of either 2-1/2% or 5% so that you can correct the secondary voltage. For example, a primary voltage of 492v can be corrected with the +2-1/2% tap so that the secondary voltage will be 208y/120. The 5% tap will correct a primary voltage of 504v. Of course your primary voltage will not be either of these exact voltage so you will have to select whether you can live with a little higher of lower secondary voltage.
Likewise, (4)2-1/2%FCBN taps provide the ability to compensate for the more common problem of low transformer primary voltage in (4) 2-1/2% steps.
 
Re: FCBN taps

I agree with Iwire's reply about using a Voltage Boosting Autotransformer setup (AKA "Buck/Boost"), as opposed to changing the taps on the power Transformer.

The consern (to me) lies in what will happen to Equipment connected L-C (120 VAC devices), with this new configuration.

Also, the Boost Autotransformer will not require system shutdown, and can be placed in convenient location - more targeted to serve the intended load.
Using the Boost Transformer, you will be able to achieve upto 15% Voltage increase - raising the Line Voltage from 208 VAC to 240 VAC, by using a 120/240V ? 16/32V Isolated Transformer setup with both windings in Series Adding, and connected in a Voltage Boosting Autotransformer method.

If connection schematics are needed, let me know and I'll attach one here.

Does this sound logical to anyone here? ;)

Scott35
 
Re: FCBN taps

Thanks for the input everyone! After running these options by the tenant, they've decided to buy equipment that's rated to match building voltage.

Thanks for the help!

LB
 
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