Low Voltage

Probably none (except possibly to your product!).

Just sort out the input voltage, or get different transformers (or use different taps on the ones you have).

You need to take steps to increase the incoming voltage to 240 volts. Check with the utility to find out what the problem is.

why do you think this is the utility companies problem? it sounds like he has a 120/208 Y system instead of a 120/240 Delta. You are usually much more acute than this.

Hard to say from the information given. If your indexer is part of a C# program, then low supply voltages might cause random data loss. If instead your indexer is part a motion control system then under voltage application concerns to the motors will depend on the type of motor used and the possible driver circuitry required to operate these motors. If instead your indexer is just somebody at work's high school student helping your secretary to file your paper documents, then the poor lighting from under voltage will help to build character and obscure your record keeping. Unless the kid is your bosses kid, then immediately find the correct transformer. You don't mess with family.

The indexer is for a CNC milling machine (operated manually because the control was not designed for a 'A' axis). Using ohms law I get E=120, I=5, and R=24. If I use it with the known voltage 203v and the ohms 24, I would get I=8.45 Am I correct in my thinking? The damage would come from heat generated by the increase of amperage.

Sort of right but..

You have an AC system which is a little different as you have to look at more things, i.e. inductive reatance, etc. The simplest thing is look at the VA rating on the transformer, at 120V 5A on primary would be 600VA transformer so it would be around 5.7A at 104V. Transformers are reasonably reliable so I dont thing this would be an issue, but is the voltage within spec for the index?

Another note worth mentioning, if the secondary is 120V at 5A, then the primary is 240V at 2.5A.

...fed with 203V from where? 240V in my experience is the voltage across both hot lines of a split phase system, as in homes. 208V is a common industrial voltage in 3-phase systems, and 203V would be within tolerance for a 208V system.

Check your incoming voltage(s) from the power company. If you do have 208V 3-phase, then you may not need the 120V transformers, as in the 208V 3-Ø system there is 120V between any hot line and ground, but make sure you don't need isolation before you actually connect anything.

Another perspective.

First, you really need to take this problem seriously and correct it. While 103 vac is within the -15% rating, an extended brown out or any low voltage situation (hot day - heavy utility usage) could cause further heating of electrical equipment and damage it.

Secondly, if this is not a component problem, ie, a quality transformer problem, perhaps it is a facilities issue. In a big plant, this could be a power distribution problem so look at your incoming service voltage and move towards your machine if the problem isn't with your provider.

Low voltage situations do cause electric equipment to have shorter life spans. Motors, etc. have a tendency to burn up.

You didn't give us the size of the transformers. If they are typical three phase or single phase transformers, check to see if the transformer has secondary taps and see if you can tap to a higher secondary voltage. Also find out where the primary power is coming from. Can you re-tap that voltage to a higher voltage?

What is your building supply voltage?

Have you run a power analysis to see if the situation is intermittent or constant?

Even a 208 voltage source should be reading around 210-212V.

Good post, but WRONG direction, you wrote:-

If they are typical three phase or single phase transformers, check to see if the transformer has secondary taps and see if you can tap to a higher secondary voltage.

He needs to patch to a LOWER VOLTAGE as input, this will give a higher output.....

Have a great day in spite of me.

You may both be right, depending on the transformer. He was referring to taps on the secondary; you are referring to taps on the primary. Some transformers have both, but I believe most have only one or the other.

I was under the impression that primary taps were being talked about. If secondary, naturally you are absolutely right and I was completely wrong..........(I just looked he was talking secondary!)

Most major equipment I worked on had only primary taps to adjust for variations in the mains......all the secondaries were "fixed".....

The OP did not mention if there were taps of any sort on either side.

I reiterate, major equipment has usually got fixed secondaries, maybe several of them, but no adjustable taps, adjusting for each secondary, as there may be several, yould be too complicated generally speaking......

Only on the primary (on good equipment) will you get a range of taps on major equipment, or none at all.

I am perfectly ready to be wrong on this (or any other point) but that was my experience.....

All Running devices like Motors, Platforms etc may be damaged by "LOW" Voltage, and to your processong control of CNC machines also

As compared to worrying about the damage that could be caused, I would recommend correcting the voltage. The transformers in question- check to see if they have primary taps. Many transformer have taps marked at 5% FCBN (meaning 5% increments full capacity below normal) If they do you can rewire the input to the -15% tap of 240v which would be 204v and then the secondary voltage will come out 120v. If not you can use a buck boost circuit designed to go from 208v to 236v with 204 in, 231v will come out and be fed into the existing transformer which should then come out at 116v. As the other post have said depending upon the design of the load the low voltage can cause degration and premature destruction of the equipment.

The low voltage condition is more likely to affect the drive indexing motor than the control electronics (usually well regulated within the unit). Check the specified operating voltage limits for the indexer and correct your input voltage problem if it is not compliant. You do not want to wait to be producing bad parts, smashing tools or worse yet jeopardizing your equipment investment (usually around $10K or more).