Having redundant power supplies helps reduce equipment down-time. In the event a power supply fails, the remaining unit will continue to power the load. A faulty power supply can then be replaced at a suitably scheduled time without shutting down the equipment.

The DRM40 series of 20-40A DIN rail redundancy module can be used in three configurations:

1. As a redundant system requiring a maximum load current of 20A. In this configuration, two 20A power supplies are connected to the DRM40 and in the event that either power supply loses its output the other unit will continue to supply the 20A load. Internally, the OR’ing FETs will block reverse currents, if one of the power supplies fails short circuit; this allows the load to continue receiving power.

• Alternatively, two power supplies can be connected in parallel and, using the current balance function, the outputs can be adjusted to provide equal current to supply a load up to 40A. Balancing the currents avoids one power supply from providing the majority of the load, running hotter and reducing its field life.

• The third option is to use two DRM40 modules to support a 40A redundant load. Here, two 40A power supplies are each connected to a separate DRM40, with the two 20A inputs connected in parallel. If either power supply loses its output, the other units will continue to supply the 40A load. Again, internally, the OR’ing FETs will block reverse currents if one of the power supplies fails short circuit, allowing the load to continue receiving power.

More information about the key features and specifications are on the DRM40 datasheet found via this link: www.emea.lambda.tdk.com/uk/drm40

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