4.4.1 Standby
The UPS output is off, but the batteries are charging, see 3.3.6 step 5
4.4.2 Normal operation
See 4.3.1.
4.4.3 On bypass
The UPS is equipped with an automatic bypass switch. This switch automatically transfers the load to
the mains if the UPS is unable to deliver the demanded output power due to overload or
overtemperature.
If all 4 load LEDs illuminate, bypass operation is caused by an overload. If only green load LEDs
illuminate (the red load LED is off), bypass operation is caused by overtemperature. Take appropriate
measures: reduce load and/or temperature.
The UPS will switch back to normal operation when the overload has been removed or the temperature
has dropped below alarm level.
If a power failure occurs during bypass operation, the UPS will switch to battery operation and
eventually, when the batteries are depleted,
output power is lost
.
The bypass function can be disabled - see 4.4.6 and 4.5 for further details.
Fail safe bypass operation:
if the UPS becomes defective, the load may be switched to bypass
(provided that the bypass function was not disabled). As the status of the UPS is unknown in this
situation the indications on the operating panel may differ.
4.4.4 On battery
The UPS uses the energy stored in the batteries: see chapter 9 ‘Batteries - runtime’.
The runtime capacity LED bar will show the remaining runtime. The UPS will shutdown:
•
after the batteries have been discharged (automatic restart), or
•
if keypad 'O' is pressed (restart via front panel required) or
•
if a 'UPS shutdown' command is given by the computer. Restart depends on the setting of the
‘auto restart’ function:
- if set ‘on’ the UPS will automatically restart when the mains returns
- if set ‘off’ a manual restart is required, either as in 4.2.1 step 1 or via the UPS management
software.
As default the ‘auto restart’ function is ‘on’. The setting can be changed using the UPS monitoring
software. For more information please refer to the manual that came with the software.
4.4.5 Battery low (end of runtime)
If during ‘on battery’ operation the 25% LED starts blinking, the batteries are nearly discharged: the
remaining runtime is less than 2 minutes (default setting, adjustable via the UPS monitoring software).
Controlled shutdown of any computer equipment is absolutely necessary at this point.
If the UPS operates at 100% load, the shutdown procedure should be completed within 2 minutes after
the 'battery low' alarm started. If only part of the output capacity of the UPS is used this period can be
longer, with aged batteries this period can be shorter.
When the batteries are fully discharged, the UPS is no longer able to power the connected equipment.
4.4.6 Bypass out of limits
The mains voltage or mains frequency are outside bypass input tolerance but inside UPS input tolerance
(see chapter 9). Bypass operation is inhibited: if for whatever reason the UPS is not able to deliver the
required output, output power is lost. If the input frequency is often out of tolerance – during which
bypass operation is inhibited and an alarm is generated – it may be useful to disable the bypass
function after which the unit operates as a UPS without automatic bypass switch. See 4.5.
