Operation; Operating Principle - LEGRAND Megaline Rack Mode D'emploi Pour L'utilisateur

2. Operation

Block diagram
Input
Input
Filter
Batteries
Batteries
2.1

Operating principle

When the mains supply is present, the input voltage is filtered and rectified by a special input stage (power factor corrector)
which is able to optimise the absorption of current from the mains, so that the power factor becomes practically unitary,
and to compensate for any shifts in voltage.
This stage is able to supply the output inverter even in conditions of very low mains voltage.
This feature becomes very striking with very low loads: with a load of around 50% nominal load, mains operation is
possible as low as about 100 V without any exploitation of battery power.
This enables more "intelligent" management of the switchover to battery power, minimising use of the batteries.
The voltage is rectified at the first stage and then taken up by a high frequency inverter to produce the 'clean' sinusoidal
output voltage, offering very low distortion rates. A rapid, synchronised by-pass circuit intervenes during peaks of
absorption above the inverter's capacity, for example when certain peripherals are switched on, demagnetisation of large
colour monitors, etc.
Should the mains voltage fail or be subject to excessive sag, a booster stage is automatically activated.
This employs the batteries and safeguards the supply of power to the output inverter, and thus to the load, without
any break. The circuitry is a passing neutral type, i.e. with no alteration of the neutral system of the appliances
connected to it.
During normal operation, a sensor verifies the difference in potential between the neutral wire and the earth wire: should
this be excessive, it will activate the input protection and switch the UPS over to battery mode, signalling the anomaly.
It is, however, possible to modify the parameters of the software so that only signalling is provided, if preferred.
All the UPS functions are supervised by a microprocessor that is also able to control and memorise certain operating
conditions, in addition to managing the UPS interface with a computer by means of a
RS 232 serial line.
This makes it possible to control the operating functions and any anomalies in real time.
The UPS keeps the operator informed regarding its operating status using visual and acoustic signals:
- alphanumeric display 1 on page 35
- status indicator 7 on page 35
- acoustic signal (located inside the UPS)
By pass
~ =
= ~
Power
Inverter
Factor
Corrector
Power
Module
=
=
Voltage
Booster
Battery
Charger
Power Module
Micro-
RS 232
processor
Interface
Logic
Remote
Control
Megaline Rack
Output
Output
Filter
31