ESP114A power supply

I recently obtained a few HP ESP114A server power supplies I intend to use for an induction heater project. These supplies are available as a surplus parts from recycling old servers and are really quite powerful for the low price they fetch on the market. Multiple output voltages, under- and over-voltage protection, short-circuit protection, over-current protection and PFC are just a few of the features. If you would want to buy a comparable industrial PSU from say Meanwell you would easily be looking at a few hundred euros for a supply with much more limited features.

The part descripiton table shows these maximum values: 12V 55A, 5V 30A, 3.3V 45A. By wiring multiple supplies together one can also acheive higher voltage (serial connection)or higher current (parallel connection) from multiple power supplies of the same type.

The power supply has a hot-plug connector on the rear where the line voltage should be connected, but also signal and output pins are on the same connector. L and N are connections to the powerline, the GND right next to them should be powerline ground. When the power is applied to the PSU the VSB power supply will already be running and so will the fan of the PSU. To power up the other outputs of the PSU the three signal pins connected with red line on the image should be shorted together. When running at full power the fan is quite loud 🙂

I have done some preliminary testing of the PSU and have verified that it is fully capable of cold-starting and running 500W (10 x 50W @12V) of halogen light bulbs 🙂 Please note that this is still ~10A below the power supply current limit, however the light bulbs usually have a starting/cold current that is a few times higher than their running current, so I won’t be pushing my luck…

The following image is showing the electrical connections to the PSU. The three small signal cables are connected together. The blue and brown wires on the left are the line voltage. The yellow-green on the left is the line ground. Black are the GND / – cables to the halogen bulbs and yellow are the 12V / + cables to the bulbs. I have used some female spade terminals on the connector, however these will heat up under heavy current (I measured 50 degrees celsia after some time @ 20A), so it would be better to get a proper connector or to simply solder a cable to the connector.