DC voltage/amp regulator

Hello, I’m looking for a way to limit DC voltage and amps to a max of 380vdc and 12 amps DC. I’m not sure if a limiter or a regulator will work but need something to accomplish this. Thank you!

We don’t have it in our system but I think TDK Lambda makes a power supply that can do this, please note you need access to 240VAC 3-Phase power for this:

Click here for PN: G400-13-3P208

Kindly reach out to somebody in our Applications Engineering team if you’re looking for a quote for this, or if you know the exact part number you need quoted, please use our Special Order Product Request Form.

I need DC to DC .

Hello @4infinitymission,

Please describe the nature of your project. For example, is this a battery powered project? Also, please describe the attached load. It this a motor with high inrush current or a resistive heater.

Understand that a project can get complicated very quickly. The 6-horsepower requirement coupled with safety will be a challenge.

Best wishes,


I’m running an EG4 mini split air conditioner/ heat pump 24k. It operates on DC from solar panels and AC input. It uses solar when available. You can only put 380vdc at 12amps to it or you will burn it up. On cloudy and winter days I’d like to have extra panels hooked up to it. If I had a regulator or a surge protector on it that would only allow 350volts DC into it I could over panel it for cloudy days! If I could restrict the amps, that would be nice but not necessary.
Rev. Scott Ertl
Infinity Mission

P.S. I have looked into surge protectors and question if they can handle doing their job on an on going basis.

Hello @4infinitymission,

Negative, surge protectors are not up to this task and the power is too high. Instead, we need some type of voltage regulator / power supply.

Let’s start with a bit of theory regarding techniques to lower voltage:

  • Linear: One way to lower voltage is to use a linear pass device. This could take the form of resistors or semiconductors. In all cases, the difference is converted to heat. As an example, if your solar array over panel efforts delivers a sunny day 400 VDC and we need to limit to 350 VDC at 12 A, the pass element will burn approximately 600 W.

  • Switching: A switching regulator is preferred from an energy conservation perspective. Instead of burning the energy, it rapidly switches the current on and off. With the proper inductive and capacitive filter elements the output is clean DC voltage at the desired voltage. Know that the switching regulator is highly complex when compared to the linear regulator.

For this application we are looking for a “Buck Converter” that can operate within the demands of your array and the EG4:

Unfortunately, this is a highly specialized application. I have been unable to locate a suitable converter.


  1. Contact EG4 at Contact - EG4 Electronics

  2. Continue searching for a buck regulator suitable for you applicaiton.

  3. As I understand, the EG4 is a hybrid AC / DC machine. Work with your solar installer to construct a transfer switch that will automatically switch between AC and DC depending on the voltage. This assumes you already have an inverter that is capable of powering the unit. Note that you will lose energy in the conversion process. However, that may not be particularly important on those sunny days.

  4. Work with your solar installer to cut out solar panel on those sunny days.

  5. Work with your solar installer to incorporate a resistor bank (linear solution) to reduce the voltage. This is highly inefficient but relatively simple to integrate. Again, the efficiency may not be important. After all, you over panel for the poor solar days, there will be energy to burn on the good sunny days.

Please let us know how you solved this problem. Kindly include pictures.



P.S. Please be careful with yourself and loved ones. Your system sound impressive but high DC voltage makes me nervous. Hence, the recommendation to always work with a licensed installer.

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Hi 4infinitymission,

We do carry a part which might work in your application - the 1866-RSDH-300-48-ND. It is a DC-DC converter which takes between 250Vdc and 1500Vdc and outputs a regulated 48V (adjustable from 48Vdc ~ 58Vdc). It’s maximum output power is 300W, so at 58Vdc, it could deliver roughly 5A.

Since the outputs are isolated from the inputs, one can configure two of these so the outputs are connected in series for a voltage of 116Vdc, while connecting the solar inputs in parallel. However, with the max output of 5A, that only provides about 580W, which is a little low for the max output of the EG4, which can operate between 190W and 1100W. If you added a third unit in series, you get up to 900W output (144Vdc at 6.25A (each unit outputting 48Vdc, 6.25A)), which would allow the EG4 to operate near its maximum capability, but would keep input voltage well below your 350Vdc max value.

As @APDahlen mentions, be very careful when working with these high voltages.

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Hello @David_1528,

Interesting solution.

I think you are correct to go with the higher voltages using 3 or even 4 such devices. There is an unknown with regards to start up current at 135% rated. Although the datasheet mentions a “hiccup” ride through that may take care of the problem.

Another consideration is efficiency. However, if we assume a high correlation between sun and the need for air conditioning this may not be a problem.



P.S. Must include a suitable enclosure with clear label for the non-standard installation.

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