N+1 and 1+1 Redundancy for 1606 power supplies

Our topic for this week’s User Group seminar is Reliable Power Delivery Inside Your Panel.  Part of that discussion is using redundant switched mode power supplies.  Here are some basic concepts of N+1 and 1+1 redundancy for the Bulletin 1606 power supplies.

When two power supplies are wired in parallel, that is generally considered 1+1.  When more than two power supplies are wired in parallel, it is typically referring to N+1.  For example: The load is 10A. 1+1 would mean two 10A power supplies are wired in parallel.  For example: The load is 20A. N+1 would mean three 10A power supplies are wired in parallel.  The “+1” is your redundant capability so that if one supply fails, you still have ample power for the load.

Another important concept to be familiar with power supplies is parallel or redundancy… Customers design redundant circuits to increase system reliability and avoid the high cost of unplanned system shutdowns.  There are 2 common methods for designing redundant power supply circuits:

1+1 Redundant System

In a 1+1 redundant system, one power supply is able to carry the entire load.  A second power supply is used as the back-up device.  Upon failure, the entire load is shifted to the second (or redundant) power supply.  For example: The load is 20A. Therefore, you would use two 20A power supplies.  If the first power supply should fail, the entire load is then supported by the second power supply.

N+1 Redundant System

In a N+1 redundant system, more than one power supply is needed to carry the load. For example: The load is 20A and you have 10A power supplies available for use.  You would need two 10A power supplies to power your 20A load.  But you need redundancy so a third 10A power supply is necessary for back-up.  In this case, the “N” would be the two power supplies and your “+1” would be the third back-up power supply.  If one power supply should fail, the entire load would be shifted to the remaining two power supplies, thus still providing 20A to the load.

Using the 1606 Redundancy Modules

By wiring an additional power supply in parallel, you now have another power supply that can power the load.  By adding redundancy module(s), you will be protecting your power supplies.  Should one power supply go down, the other power supply will provide the power to the load and the redundancy module will protect that supply from being damaged by the first power supply that went down.

There are several options for redundancy modules.

1606-XL60DR, 1606-XL120DR, 1606-XL240DR, 1606-XLRED20-30, 1606-XLRED40, 1606-XLPRED, 1606-XLSRED, 1606-XLSRED40, 1606-XLSRED80, and 1606-XLERED.

These redundancy modules provide protection from the system in case of a short on a power supply.The protection is completed by the internal diodes; they provide isolation against DC bus problems that corrupt working supplies.

The 1606-XL60DR, XL120DR, and XL240DR can be used as stand alone devices in redundancy.  These units are basically the power supply and the redundancy module in one device.  The 1606-XLRED20-30, 1606-XLRED40, 1606-XLPRED, 1606-XLSRED, and 1606-XLERED redundancy modules need to have a 1606 power supply feeding the input.

Here are several application notes on using the Redundancy Modules to reference: