Emerson 7400 - Manual (Page 24)

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Series 7400 Single Phase 1+N UPS
2.1 Introduction
Starting and stopping the one-plus-one system is straightforward,
however the modules’ response depends on whether it is
configured as a Redundant or Non-Redundant system. The
operating procedures are the same irrespective of the selected
redundancy mode; in simple terms you start (stop) one module and
then repeat the operation on the second module.
The difference in the system response concerns the point at which
the load is transferred between the bypass and uninterruptible (i.e.
inverter) supplies and is summarised below: -
Starting:
When starting a redundant module system the load is transferred
from the bypass to the inverter of the first module as soon as the
first module is started and its inverter is brought on line. When the
second module is started its static bypass line is totally inhibited
due to the first module being on line, and the second module will
not be connected to the load until its inverter is operational and fully
synchronised with the first module.
Stopping:
When the first module is stopped its static bypass is inhibited
because the load will be fully maintained by the inverter of the
second module. When shutting down the second module, the
static bypass lines of both modules will be turned on as soon as its
inverter is stopped. That is, both modules will provide load power
through their paralleled bypass lines.
Starting:
In a Non-Redundant module system both modules must be running
before the load is transferred to their paralleled inverters. Therefore
when the first module is started the load will remain connected to
its static bypass line.
Stopping:
The load will be transferred to the static bypass lines in both
modules simultaneously as soon as the inverter stops in the first
module to be shut down.
Note 1: All the user controls and indicators mentioned these in these procedures
are identified in chapter 1.
Note 2: The audible alarm may annunicate at various points in these
procedures. It can be cancelled at any time by pressing the ‘Alarm Reset’
pushbutton.
Note 3: The 7400 series UPS incorporates an optional automatic boost charge
facility which can be used in systems containing non-sealed lead-acid batteries.
If this type of battery is used in your installation you may notice that the battery
charger voltage will be greater than its nominal 432Vdc when the mains supply
returns from a prolonged outage. This is the normal response of the boost
charge facility: the charger voltage should return to normal after a few hours.
2.1.1 Redundant
Module System
C h a p t e r 2 C h a p t e r 2
Operating Instructions
2.1.2 Non - Redundant
Module System
2.1.3 General Notes