Are external fuses required on the input of PS5R or PS3L series power supplies?

As there are internal fuses on the input of these power supplies, an external fuse is not required. However, the internal fuse is not field replaceable since it is soldered to a PCB. Therefore use of an external fuse is often preferred as it can replaced easily if necessary. Values for internal fuses are listed in the catalog specifications.

What are the differences between Linear and Switching (aka Switch Mode) Power Supplies?

IDEC only manufactures Switching Power Supplies. Switching power supplies differ from linear power supplies primarily in how the primary voltage is tranformed into the output voltage. Switching power supplies use a high speed switch (power transistor) to produce a high frequency voltage that is passed through a relatively small transformer and then filtered to remove the AC component and noise. Linear Power Supplies simply pass the original primary voltage (ie 120VAC/60Hz) directly through a relatively large transformer and then filter it to remove the AC component. In general, switching power supplies are considered superior due to their higher efficiencies, lighter weight, ability to handle wider input voltage ranges, and longer hold up times. Linear power supplies are sometimes less expensive, particularly on larger wattages. One concern in using a switching power supply is the high frequency noise (EMI/RFI) that they produce, but this effect is reduced by adequate filtering.

Can I put multiple IDEC power supplies in parallel to increase the total wattage capacity?

Yes. Diodes are recommended on each output to prevent voltage imbalances from feeding back from one power supply into another. No more than 5 power supplies should be paralleled together. In the PS5R series, only the 75W, 120W, and 240W models should be paralleled and only same wattage models should be paralleled with each other.

Is it possible to parallel models of different wattages together?

Only models of the same wattage should be paralleled. Variations in various specifications can cause problems when paralleling dislike models. For example rise time, hold up time, input and load regulation vary depending on model. Such variations can result in one unit trying to carry the whole load and going into overload shutdown.