FAQs - Computer Room Electrical Power Projects

Electrical power and efficiency information for critical structures in server rooms.

PDU stands for power distribution unit and there are several types including basic, metered and intelligent. PDUs are available for single and three phase loads which are connected to socket outlets or hardwired connections on the PDU. Each socket is metered and the information gathered can be reported over an SNMP (simple network management protocol) IP network. The information can include voltage, frequency, phase, load in KVA and kW and the energy drawn in kilo-Watt hours (kWh). When a PDU is referred to as intelligent this generally refers to the ability to remotely control at the outlet socket level, giving an IT manager the ability to remotely power off an outlet or reboot a server.

External UPS maintenance bypass switches provide an ideal way to isolate an uninterruptible power supply for maintenance or swap-out without disruption to the connected loads. The bypass switch should be a make-before-break (MBB) type but break-before-make (BBM) can also be installed where the load is not sensitive to micro-breaks in power. Most UPS maintenance bypass switches below 16A are available from UPS manufacturers for either wall mounted or 19inch rackmount.

Automatic transfer switches have two power sources (A and B) and use one of these to power their connected loads. The two power sources can be two UPS systems or two mains power supplies or a combination of the two. If one of the power sources fails, the other is automatically switched in. Automatic transfer switches are an ideal way to add a further level of resilience to a server installation and ones up to 30A can typically be rack mounted making them ideal for server cabinets.

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