7400 Series UPS User Manual Chapter 2 - Operating Instructions
Single Module and One plus One Systems Introduction
6310018a.02.doc
2-1
Issue 2
(02/98)
2. Chapter 2 - Operating Instructions
2.1 Introduction
The UPS can be considered to be in one of three operating conditions:
• Shutdown - All power isolators and circuit breakers open - no
load power.
• On Maintenance Bypass - UPS shut down but the load connected
to the unprotected mains via the Maintenance Bypass Supply line.
• Normal operation - All relevant power isolators and circuit
breakers closed, the load is powered by the UPS.
This chapter contains detailed instructions to enable you to switch
between these three conditions.
Note 1: All the user controls and indicators mentioned in these
procedures are identified in chapter 1 (figures 1-3, 1-4, 1-7, 1-8 and 1-9).
Note 2: The audible alarm may annunciate 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 normal
value when the mains supply returns from a prolonged outage. The
revised voltage will be 460V d.c. for a 380V a.c. system, 475V d.c. for a
400V a.c. system and 490V d.c. for a 415V a.c system. This is the
normal response of the boost charge facility: the charger voltage should
return to normal after a few hours.
2.2
One plus One
Starting and stopping the one-plus-one system is the same as a single
module, 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:
2.1.1 General notes
2.2.1 Redundant module
system
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