No-Load Loss of Welding Transformer

Three months @ 0.5kW @ £0.15GBP/kWh is £164 per quarter, or £660GBP per year.

Switching it off costs nothing.

Just switch the thing off when it is not in use!

I have already installed auto ON/OFF circuit, but I want to project my job to my siniors. So I want to add some more advantage in my presentation.

I am working in process plant and nobody bother to switch off the set frequently. In a span of 8 hrs shift, only 2 to 3 hrs are actual welding hrs. but the machine is kept on throughout the shift. I am saving about 4 hrs per shift per welding set.

Worrying about the powered idle time of welding sets doesn't feel like a fulfilling job role here...

I have to agree. If OP figrues in the cost of time to turn unit on and off with every use, it may be a wash, $ wise.

Finding a way to utilize the welder more efficiently may make bigger points.

With the lack of information here, it's had to have an opinion.

Remember, the cooling fan has a purpose. Turning it off when not running the welder may shorten the life of the equipment.

What does the manual say?

I bet if you really looked around you could find far greater power wasting devices and actions than the 500 watts or so the welder uses at idle.

The other thing is many welders do not run the main power transformer at idle it's just switched on and off with the welding function. The 500 watt usage is probably mostly just the fan motor running that is using the power.

Put a time delay relay on it and have it triggered from the control circuit side of the system. Have it time out and turn the fan off a few minutes after the welding is done.

Its more keeping the capacitors charged, as well as running the controll electronics. Most cooling fans are thermostatically switched.

Most welders keep a set of caps charged to smoothe out the power demand. Units with Power factor correction (on Miller for example) uses many caps to cut welding power by as much as 45% @ full power, but increase idle power by about 20%.

Actually I am interested in current (amps) it draws in no load condition - 5amp to 7amp

Is there any saving in terms of VAR? if it is there what is the way to calculate in terms of money?

A timer is already there which switches off the device after say 60 sec.

The other advantage of putting the machine off for most of the time, is safe plant condition. There are many cases where users were electrocuted while using welding set.

"There are many cases where users were electrocuted while using welding set."

Goodbye!

To evaluate the savings you need to see how your company charges for electricity, since you mentioned that you generate your own power. In my area of the world, we pay for power by (1) the kW-hrs used, and (2) the kVA demand peak observed over the course of a month. In your case, the VAR would contribute to the kVA demand, and if it added to the peak drawn over a month it would cost you some money. Since this is not very likely with your low current draw I'm not sure that it would even be observable in your power situation. ---Unless welding machines present a poor power factor when under load. If they are like motors, then the power factor rises from a poor number (yours was .12) up to something more acceptable like 80% when under load.

I have always watched the total power factor presented by the plant since this was what we paid for with our kVA charge. But our kVA demand is built up of motors drawing large loads.

I think your word "electrocution" probably should have been "electrically shocked" as your comment seems to have electrocuted some of our posters!! I presume that your welders have not died from touching welding voltages? The English word for this type of non-fatal electrical contact is "shocked" or "electrically shocked". It is a pretty standard occurence with maintenance welders in a situation who have to weld equipment in the rain.

Jon.

The current being drawn by the welding machine during the "off" state is largely due to the cooling fan consumption as stated previously.

On most of the welding machines I have worked on over the years and currently work on, the cooling fan(s) stay on continously to prevent residual heating damage to the machine windings and filter network.

Other than initial charging current and very minor insulation leakage, the filter network does not consume power.

Shutting down the welding machine at 60 Seconds after use will circumvent the cooling affect of the fans on all machine components and the machine life will be dramatically shortened.

Length of the cooling cycle "cool-down" time is dependent on machine insulation rating, ambient temperature, and length of duty-cycle (use).

Therefore it will take the machine several minutes for the fan(s) to properly cool the components after use.

If you are going to automate the "on/off" function, you should look at the cooling section of the machine control circuit and make sure the cooling fan(s) operation is controlled by a temperature switch that allows shut down only after the machine has cooled off to factory recomended temperature.

As for user being "electrocuted"; Definition of electrocution is "death by electrical contact"

Are you really having that many instances of electricution or are the users just receiving an electrical contact shock?

Automating the "on/off" function of the machines will not in any way affect the incidence of electrical contact during usage as this is a function of negligence and/or ignorance by the user. (no gloves, wrong gloves, unsafe wet condtions, damaged/unsafe welding leads or stinger, or plain old willful disregard of proper welding technique(s).) (You/we can't fix "stupid".)

Automating the "on/off" function will help prevent inadvertant contact with improperly stored welding leads/stingers.

Sounds like your site needs some serious mentoring, education, and adoption and enforcement of better safe working rules.

Good luck and stay safe.

Instead of trying to save money you should find a way to improve productivity.

The idle time of the welding apparatus represents an under utilisation of an asset.

Putting the machine to work for 8 hours every shift will make more money running than you can save by turning it off when not in use.