Powerware SOLA 4000 manual Maintenance Bypass, Hot-Standby Systems

SOLA 4000 - General System Description

1 UPS Assembly

1.7 Maintenance Bypass

The maintenance bypass function is to supply power directly to the connected load during UPS maintenance. The bypass consists essentially of one switch IBY.

With SOLA 4000 series UPS systems, switching from different operating modes to maintenance bypass can be performed without interruption. With the maintenance bypass on, the UPS system may be completely switched off, thus permitting maintenance work to be carried out safely ( there will only be voltage at the input and output terminals and their connections to the circuit-breakers).

In order to prevent erraneous switching of the maintenance bypass switch IBY that could possibly cause parallel connection of the bypass line and the inverter line, IBY is electronically intercon- nected with the static inverter switch SSI. Thus, during actuation of IBY, switch SSB will be closed and switch SSI opened automati- cally, preventing parallel operation of the maintenance bypass network and the inverter.

As an option, an external wall-mounted no-break maintenance bypass switch (see FIG. 1.6.1) may be supplied by SOLA.This switch provides simple one-step transfer to maintenance bypass (version 1) without the possibility of erraneous switching and without interruption to the load.For the version 2 type maintenance bypass, an additional position is provided in order to completely isolate the UPS with the one bypass switch.In this way, the UPS may be isolated totally from all supply by switching off the input supply to the UPS.

1.8 Hot-Standby Systems

A hot-standby UPS system basically consists of two (or more) single UPS units which operate independently of each other. Any one unit can be feeding the load at any time.

•All units are continuously in operation; but only one is supplying the load, at any one time.

•In case of a failure in the unit currently supplying the load, another unit is ready to takeover the load without an interrup- tion on the output side. i.e. the load is still supplied with condi- tioned and stabilised power.

•The load is supplied by the static bypass, only if there is no inverter ready in the system to takeover the load.

JUE 401264 10