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INFOSEC UPS SYSTEM - 4, rue de la Rigotière - 44700 Orvault - FRANCE - www.infosec-ups.com
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3.3
Operating principle.
The M4T UPS series is a double conversion system AC/DC, DC/AC with a sine wave output that gives safe
protection in extreme power supply conditions (variations in voltage, frequency, electrical noises, blackout and
micro cuts, etc…). Regardless of the type of load to be protected, these devices are designed to ensure a
quality and continuous power supply.
The operation is as follows:
An IGBT three phase rectifier converts the AC voltage into DC by absorbing a pure sinewave current
(THD <2%) and charging batteries at constant current / voltage.
The batteries supply the power needed by the inverter in the event of mains failure.
The basic double conversion structure is complemented by two new functional blocks, the static bypass
commuter switch and the manual bypass commuter switch.
The static bypass commuter switch connects the output load directly to the bypass network in special
circumstances such as overloading or overheating and reconnects it to the Inverter when normal
conditions are restored.
The M4T-B version has separate lines for the Inverter and bypass blocks, thus increasing the safety of
the installation as it allows the use of a second power supply (generator unit, other electricity company,
etc.).
The manual bypass commuter switch isolates the UPS from the mains and from the loads connected to
the output, so that maintenance operations may be performed on the UPS without any need to
interrupt the supply to the loads.
3.3.1
Normal operation, (
)
.
When there is a mains power supply, the rectifier transforms the AC input voltage into DC raising the DC
voltage to a suitable level to supply the inverter and to charge the batteries.
The inverter transforms the voltage of the DC bus into AC, providing a sine wave alternating output, stabilised
in voltage and frequency to supply the loads connected to the output (figures 10 and 11).
3.3.2
Operation with mains failure,
(
).
In the event of mains failure or should a micro cut occur, the group of batteries supplies the power needed to
supply the inverter.
The inverter continues working normally without being affected by the lack of mains and the back-up time of
the device depends only on the capacity of the group of batteries (figures 10 and 11).
When the battery voltage reaches the end of back-up time, the control blocks the output to protect against
deep battery discharge.
When mains is restored and after the first seconds of analysis, the UPS again operates as described in the
“Normal operation” section.
3.3.3
Operation with inverter not active,
(
).
The inverter is inactive due to the existence of alarm conditions such as overloads, overheating, end of back-up
time, etc. In this case the rectifier continues charging the batteries to maintain the optimal charge.
The inverter is also inactive if the unit has not been started up with the keyboard. In that case, the rectifier will
be inactive.
In all these cases the output voltage of the UPS is supplied by the emergency bypass line through the static
bypass commuter switch (figures 10 and 11), provided that the EPO is inactive
3.3.4
Operation in manual bypass,
(
).
When maintenance checks are to be performed on the device, it may be disconnected from the mains without
any need to cut the power supply to the system and affect the critical load. The UPS may only be worked on by
technical or maintenance personnel, by means of the maintenance bypass (as per specific instructions for that
purpose).
Summary of Contents for M4T
Page 1: ...User Manual 10 80 kVA ...