16A Maintenance Bypass Switch

The 16A Maintenance Bypass Switch allows the connected UPS to be taken out of circuit whilst maintaining power to the connected load.

MBS Diagram


1. Mains Input

The incoming mains power connection. Connect to the mains via the plug to IEC C19 connector (supplied).

2. UPS Input

This is the mains supply to the UPS. In order to maintain suitable ratings the UPS should be a 3KVA UPS System with a 16A input. Connect to the UPS using an 16A IEC-IEC loop lead (not supplied).

3. UPS Output

This is the power from the UPS. Connect from the UPS 16A outlet to this connector using a 16A IEC-IEC loop lead (not supplied).

4. Switch

This switch has 2 positions, Normal and Bypass.

In normal position, the power is delivered from the UPS Output connector in 3, to the master and slave outlets (see below).

In bypass position, the power is delivered from the mains input connector in 1, to the master and slave outlets.

This is a break before make switch. This means that there is a slight loss of power to the load when switching. This is in the order of 2 mains cycles maximum. Usually IT equipment does not have any problems with such fast switch overs. This also prevents accidentally back-feeding power from the mains into the output of the UPS.

5. Master/Slave Function

Note the master/slave function is optional and is not on all versions of the Power Inspired Maintenance Bypass Switch. If the master / slave function is enabled then power is removed from the slave outlets if the load on the master outlet should fall below 20W or so. The purpose of this is to allow for non-essential equipment to be removed from UPS support to extend battery life in the event of a power outage. Useful, for example if a server connected to the master outlet has been shut down.

If disabled the master and slave outlets behave as one.

NOTE: Switching the master and slave button when equipment is connected may result in power loss to any slave connected load. The master load outlet is unaffected.

6.  Master Outlets

Connect essential equipment to the master outlets. Power will always be available on both the 16A and 10A IEC outlets in normal operation.

Mains Input UPS Output Switch Position Master Output Voltage

7. Fuses

The maintenance bypass switch is rated at 16A. The 10A fuses are necessary in order to protect cables and connectors connected to the 10A IEC connectors.

8. Slave Outlets

If the master outlet power consumption is above 20W the slave outlets will be on, regardless of the position of the enable/disable switch.

If the master outlet power consumption is below 20W the slave outlets will be off, only if the Master/Slave Function is enabled.

9. Rack Ears / Wall mount lugs.

The unit comes supplied with the rack ears on the front of the unit for connection to a standard 19in rack. To wallmount the maintenance bypass switch, remove the rack ears with a pozi screwdriver and connect them to the rear of the unit using the same screws. Remember to use suitable wall supports and screws/washers to cover the rack mount holes in the rack ears.

Maintenance Bypass Switch in Wallmount Configuration

Example Schematic and Mode of Operation

16A-Maintenance Bypass Switch Schematic

Input Mains to UPS input are connected permanently.

Note the switch is 4-pole rotary, 2 for live, 2 for neutral but only 2 for live are shown.

Switch in bypass mode (shown) in diagram, input mains is connected to pin4, to pin2 and then out to the master socket.

UPS output is to pin 1 and not connected.

Switching to normal, the master power is now changed from pin 2 to pin 1 and therefore is now connected to the UPS output. At the same time, due to switch linkage, the mains power is removed from pin 4 (and hence pin 2) and is on pin 3 and not connected.

You can see (possibly) that you could in fact do this with one double throw switch, but the problem arises if an arc is drawn during switching. In such cases the arc would cause a short between input mains and UPS output, damaging the UPS.