transformer boosting

[jimtech67]

I am looking for a transformer to boost AC voltage from 120 volts to about 150 volts. My VA requirements are small below 250 VA. Or does a small battery backup exist that I can use? Can some one point me to a source?

Jim

 

[Steve Bailey]

If you have 240 VAC avaliable, you could use a variac.

What do have that requires 150 VAC?

 

[jimtech67]

We have a 120 volt supply. The customer is concerned about momentary voltage drops and small surges. I am powering a Mitsubishi Alpha 2 PLC voltage input range (power) is 100 to 240. We are looking for cheap way to maintain the PLC powered without getting into expensive constant voltage supplies. The only load is the PLC all outputs are dry contacts. This a small application. I need something small if possible to fit in our box.

Jim

 

[Steve Bailey]

I don't understand what you hope to accomplish by boosting the supply voltage.

 

[Jim Dungar]

You can use a buck-boost transformer arrangement to boost your voltage by 26.6% (120->152V). A Square D 100SV46A transformer will provide an output of 2.43A at 152V, but it will cost you almost $200US after installation.

You can get a small UPS from Tripplite for about $100.

 

[jimtech67]

If the supply to the PLC is boosted when the voltage drops it will still be in the range for the PLC to operate. I know this sound hokey but we are trying to meet our customers requests as they evolve after each demo.

Jim

 

[Steve Bailey]

Get a small 240/120 transformer and reverse the primary and secondary. Newark lists some 120 volt variacs for under $100 that will boost to 140 volts. If its short duration dips, how about a capacitor?

 

[bernie_carlton]

How about a ferro-resonant transformer (constant voltage), or have they gone out of style?

 

[Terry Woods]

Since you want to try it this way...
Try a Variable AutoTransformer for about $30.00

http://www.elect-spec.com/trnauto.htm

Since the VA is so low you might try Radio Shack for even cheaper devices.

 

[Vetteboy]

Have you considered a small UPS? Probably a lot more stable for your setup than a voltage boost. I'm sorry, I hate to try answer a question with another question.

 

[Vic]

A Buck-Boost transformer is cheapest and most reliable.

A 120/32 volt transformer connected in a boost configuration will give you 152 volts out with 120 volts in. A 75 or 100 VA will be large enough and should cost less than $50.

If the transformer primary is H1 and H2 and the secondary is X1 and X2, connect H2 to X1 and apply 120 volts to H1 and H2. The 152 volt output is at H1 and X2. If you get 88 volts output, the transformer is connected to buck instead of boost. Reverse the X1 and X2 connections.

 

[randylud]

Regulating

If you are trying to prevent system shut down due to voltage dips, you need to regulate the line and there are several ways to do that. Some are more expensive than others but you might want to look over what Sola has to offer. They make regulating transformers of the ferro-resonant type that a previous post mentioned. I have used these quite successfully in more than a few PLC applications.

 

[panic mode]

I'm with Vetteboy, why not simply use small UPS?
We usually get the 575VA UPS for our PCs for $125 Canadian
which according to currency excahnge webside is under $90US.
I am sure if you call few of your local PC distributors
you will get same deal.

panic mode

 

[shooter]

use a very simple and cheap moving transformer this will boost up the voltage to 230 volts inside the power supply there is a diode bridge and a capacitor they will be loaded twice as high and give enough solution for it i hope.
check that transformer is 60 Hz.

 

[venkat2k]

If you are looking to just get 150V ac, and think it is what you absolutely want. You could put in a 30V AC transformer and add the secondary to the supply line this will give you 150V. ofcourse the variantions in the line side will affect the summed output. This should not matter since the supply range will be within spec to what you want. I would use an isolation transformer when I do this arrangement.

I think Vic is also talking about the same thing.