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21
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1
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Power Supply PS1000-A6-24.5
Application Notes
25.5
Parallel Use for Redundancy
1+1 Redundancy
Devices can be paralleled for redundancy to gain higher system availability. Redundant
systems require a certain amount of extra power to support the load in case one device fails.
The simplest way is to put two devices in parallel. This is called a 1+1 redundancy. In case
one device fails, the other one is automatically able to support the load current without
any interruption. It is essential to use a redundancy module to decouple devices from each
other. This prevents that the defective unit becomes a load for the other device and the output
voltage cannot be maintained any more.
1+1 redundancy allows ambient temperatures up to +70°C.
Pay attention that leakage current, EMI, inrush current, harmonics will increase when using
multiple devices.
Recommendations for building redundant power systems:
•
Use separate input fuses for each device.
•
Use separate mains systems for each device whenever it is possible.
•
Monitor the individual devices. Therefore, use the DC-OK signal of the device.
•
It is desirable to set the output voltages of all devices to the same value (± 100mV)
or leave it at the factory setting.
N+1 Redundancy
Redundant systems for a higher power demand are usually built in a N+1 method.
E.g. four devices, each rated for 5A are paralleled to build a 15A redundant system.
Pay attention that leakage current, EMI, inrush current, harmonics will increase when using
multiple devices.
Keep an installation clearance of 15mm (left / right) between two devices and avoid installing
the devices on top of each other.
Do not use devices in parallel in mounting orientations other than the standard mounting
orientation or in any other condition, where a reduction of the output current is required.
For N+1 redundancy the ambient temperature is not allowed to 40°C.
