UPS Maintenance Bypass Switches
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 Power Distribution Units

UPS Maintenance Bypass Switches

External UPS maintenance bypass switches allow uninterruptible power supplies to be isolated during UPS maintenance and general service work without disruption to the load.

Most UPS above 5kVA include some form of internal UPS maintenance bypass facility but an external device allows the UPS to be completely removed from the electrical circuit if required for upgrade or swap-out.

Our UPS maintenance bypass switches are designed to support the uninterruptible power supplies and brands we supply. Some of our bypasses are sourced directly from the UPS manufacturer and others are manufactured within the company. Custom designs are available including Castell interlocks, volt-free contact alarm signals, visual meters, local AC service engineer power sockets and parallel UPS installation support.

Some of the UPS maintenance bypasses in this collection have sockets for ‘plug and play’ installation and above 3kVA they will be hardwired, requiring electrical installation by a qualified electrical contractor.

It is very important to match to maximum input rating of the UPS to the bypass amperage rating. Each maintenance bypass in this collection shows the phases and Amperage rating as per the table below:

Numeric Input Supply Output Supply
11 Single Phase Single Phase
31 Three Phase Single Phase
33 Three Phase Three Phase

Our engineering team includes certified electrical contractors allowing us to provide a complete ‘in-house’ electrical installation for any maintenance bypass and LV switchgear panel arrangement. In addition the EcoPowerSupplies design team can customise our bypass switches to meet your specification.

For further information on the UPS maintenance bypasses and LV switchgear we manufacture please call the Eco Power Projects team on 0800 612 7388, complete an enquiry form form or email us.

Item price range:

£ 179 — £ 461

Order by:

UPS Maintenance Bypasses Guide

The following table matches each of our maintenance bypasses to the relevant UPS. Remember to choose a wall mounted or rack mounted version to match your UPS installation format. Also ensure you purchase the right UPS bypass switch for your your input and output supply configuration.

Bypass UPS Size
10A 11 700VA-1kVA
16A 11 2.2-3kVA
32A 11 5-6kVA
63A 11* 6.5-12kVA
63A 31 6.5-15kVA
63A 33 10-30kVA
125A 11 27kVA
125A 31
125A 33 40-80kVA
200A 31
200A 33 120kVA
250A 33 160kVA
400A 33 250kVA
400A+ On application

Note: * if these UPS are installed in a 3/1 (three phase input/single phase output configuration) the relevant 3/1 maintenance bypass must be selected. Please contact us if you need further information.

Above 250kVA switchgear panels are supplied.

UPS Maintenance Bypass Notes

Some uninterruptible power supplies include a built-in maintenance bypass facility. This allows the UPS to be serviced and maintained ‘in-situ’ without a risk down disruption to the connected loads or maintenance engineer themselves.

An external maintenance bypass switch of the type in this collection, allows the UPS to be fully isolated and powered down, without disruption to the load. This means that the UPS itself can then be fully powered down and removed safely for either an upgrade, swap out or board replacement on site.

Care has to be taken when selecting a UPS maintenance bypass to match the correct version (single or three phase) to the UPS and the correct rating. In addition the UPS should ideally be of the make-before-break variety (rather than the lower cost break-before-make type) to ensure that the connected loads do not see any break in supply when transferring from or to the output of the UPS.

Maintenance bypasses can be wall mounted, rack mounted or built into LV switchgear and distribution panels. They can also be integrated with sockets or hardwire terminals to provide a power distribution unit (PDU) arrangement.

Castell Interlock Options

Our UPS bypasses can be built with two types of optional Castell Interlocking arrangement.

Option 1 – a trapped Castell key with auxiliary contacts for connection to a UPS remote bypass signal with a Castell bolt on the external bypass switch. Turning the Castell key on the UPS maintenance bypass switch operates the AUX contact (N/O or N/C) and generates a remote bypass signal. The key is now free and can be used to release the interlock bolt on the bypass switch of the external UPS maintenance bypass switch. The UPS maintenance bypass switch has AUX contacts in series with the Castell AUX for remote bypass signalling.

Option 2 – a trapped Castell key solenoid which is released when a “UPS in bypass” signal is generated from the UPS (key free when UPS in bypass) and Castell bolt on the external maintenance bypass switch. This will require a 24Vdc Normally Open contact to close when the UPS is in bypass. This releases the Castell key and operates the AUX contact (N/O or N/C) to give a remote bypass signal to the UPS. The key is then free and can be used to release the interlock bolt on the maintenance bypass switch of the external UPS bypass switch. The switch also has AUX contacts in series with the Castell AUX for remote bypass signalling.