MF615 - Magna Force

• DCC Power Supply Tests
• Buy Magna Force MF615

The Model MF615 transformer was tested for output voltage and current capability. It is rated at 15 VAC at a 5 amp load. I confirmed that it meets its stated specifications, and can be used for short periods at currents as high as 8 amps. It has built in over current protection that appears to operate correctly, and does not appear to have dangerously high hot spot temperatures even when used beyond its ratings.

Below is a graph of the transformer hot spot temperature vs time at a constant 6 amp load. It shut down after about 102 minutes. The voltage just prior to shut down was 14.25. This value is within the ratings of NCE, Digitrax, and Lenz for use with their boosters. I let it cool slightly and then turned it on with no load. The voltage was 16.86, just about the same as at the start. When it shuts down due to over temperature, it will not allow load current until it has cooled off a little bit, about 5 minutes or so.

I also ran the transformer at 5 amps until the temperature stabilized. It took 2 hours and 37 minutes to achieve a steady temperature of 66.3 C, but it did not shutdown at this load. The output voltage at the stabilized temperature was 14.61 volts with a load of 5 amps. This is slightly under its rating, but more than adequate to operate the NCE, Lenz, and Digitrax booster trio.

The graph below shows the load regulation from no load to a maximum load of 8.64 amperes. At the maximum load, the output was 13.78 volts. This is still within the operating requirements for NCE and Digitrax boosters, although it is slightly below the Lenz 14 volt minimum requirement. At the 8.64 amp load, the unit shut down after 9 ½ minutes. The hot spot temperature was about 40 C. Note that the hot spot is the hottest spot on the outside of the transformer, and may not be the same as the hottest internal temperature. It is located underneath the unit, so it is unlikely to be directly touched unless you pick the unit up. Directly touch accessible areas are cooler, and in general feel very hot but not enough to cause a burn. For your easy conversion, 70 C is about 160 F. 40 C is slightly above body temperature.