14
Operation
Working modes
The UPS has four distinct modes of operation:
■ On-line mode
■ Bypass mode
■ Battery mode
■ ECO mode
Each operating mode is described below.
On-Line mode
This is the default mode of operation in which the load is supplied via the inverter when the a.c. input and
load are within their normal ranges. The battery is float charged in this mode.
During fault conditions the UPS automatically switches to either bypass mode or battery mode without
interruption to the load.
Bypass mode
In bypass mode the load is supplied directly from the a.c. mains input and the battery is charged. The
UPS switches to bypass mode when any of the following conditions occur:
■ An output overload – the unit beeps twice every second, indicating that the load must be reduced to
within its normal range as soon as possible. Once the overload is removed the inverter re-starts after
a 5 minute delay. If the UPS is overloaded too many times in any one hour it will eventually remain in
bypass mode.
■ The UPS is too hot – the UPS reverts to on-line mode as soon as the unit temperature returns to
normal.
■ The UPS fails – a serious fault has occurred within the UPS that must be repaired.
■ The UPS is turned off.
In bypass mode the Inverter LED is off and the Bypass LED is on.
Battery mode
In battery mode the load is supplied from the battery via the inverter, the UPS beeps every 3 s, and the
rectifier and charger are turned off. The UPS switches to battery mode when there is no a.c. input or the
a.c. input is outside its normal range. On the front panel the Mains LED is off and the Battery LED is on.
When the battery reaches a preset low limit, the system gives a low battery voltage alarm signal, the LCD
provides a low battery alarm, and the UPS beeps every second. Eventually the UPS shuts down to
prevent damage to the batteries.
When the a.c. mains is restored the inverter starts automatically and the UPS reverts to on-line mode. If
you turn off the UPS in battery mode it restarts in bypass mode and you must press the ON button to start
the inverter.
ECO mode
Your UPS may be set to operate in ECO mode instead of on - line mode. In ECO mode the
load is supplied via the bypass circuit and not the inverter, allowing the UPS to work at higher efficiency.
The battery is float charged in this mode. If the a.c. input is lost or goes beyond its normal range the
UPS automatically switches to battery mode, however, the transfer speed is slower than on-line mode
and may not be suitable for all applications.
VFI-KT Series User Manual
