Operation; Operation Modes - MAKELSAN PM Series User Manual

PM SERIES

4 OPERATION

4.1 Operation Modes

The UPS is a double-conversion on-line UPS that may operate in the following alternative
modes：
• Normal mode
The rectifier/charger derives power from the AC Mains and supplies DC power to the inverter
while floating and boosting charge the battery simultaneously. Then, the inverter converts
the DC power to AC and supplies to the load.
• Battery mode (Stored Energy Mode)
If the AC mains input power fails, the inverter, which obtains power from the battery,
supplies the critical AC load. There is no power interruption to the critical load. The UPS will
automatically return to Normal Mode when AC recovers.
• Bypass mode
If the inverter is out of order, or if overload occurs, the static transfer switch will be activated
to transfer the load from the inverter supply to bypass supply without interruption to the
critical load. In the event that the inverter output is not synchronized with the bypass AC
source, the static switch will perform a transfer of the load from the inverter to the bypass
with power interruption to the critical AC load. This is to avoid paralleling of unsynchronized
AC sources. This interruption is programmable but typically set to be less than an electrical
cycle e.g. less than 15ms (50Hz) or less than 13.33ms (60Hz).
• Maintenance mode (Manual Bypass)
A manual bypass switch is available to ensure continuity of supply to the critical load when
the UPS is out of order or in repair. This manual bypass switch is fitted for all UPS modules
and bears for equivalent rated load.
• Redundancy mode
Based on different demands, The UPS can be set as N+X redundancy mode to increase the
reliability to the load connected.
• LBS (Load Bus Synchronization)
The function of LBS is to keep the output of two independent UPS systems (single unit or
multiple units) in synchronization even when the two systems are operating on different
modes (bypass/inverter) or on batteries. It is usually used with an STS (Static Transfer
Switch) connected to the critical load to achieve Dual Bus configuration.
UDD-SD-125/ Release Date: 20.01.2015/Rev No: 0/Rev.
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