Liebert Hinet 10kVA, User Manual

Page: 12 / 43

Hinet UPS User Manual
Page 2
(12/01)
1.2.1 Principle of operation
Normal operation
During normal operation, i.e. when the UPS input supply is present and within specification, both the converter and
inverter sections are active and the automatic by-pass is turned on to connect the inverter output to the critical load
terminals. The battery fuse-holder switch is also closed and the battery is therefore permanently float charged at the d.c.
terminals voltage level.
Mains Failure
If the mains has a failure or is out of tolerance the converter will be supplied from the battery, while the inverter will
continue to operate for a period of time which depends on the load and the capacity of the battery. If the mains supply
has not returned within this time, the inverter will go off automatically and an alarm condition will appear on the UPS
operator control panel.
Critical load will not be interrupted in the event of a drop or return of the AC power mains.
Return of power mains
When the mains returns within the required tolerance, the converter will be automatically supplied from mains,
supplying power to the inverter and recharging the battery at the same time. There will be no interruption of the critical
load.
UPS fault
In the event of an inverter failure, the automatic by-pass will automatically transfer the load onto the mains with no
interruption. In such an event, request qualified technical assistance.
The load will be transferred with no interruption if the inverter is synchronised with the mains; if this is not the case,
there will be an interruption of some milliseconds.
The intervention of the automatic by-pass line is shown on the front panel by the yellow led on.
WARNING
CAUTION: When the load is being supplied from the bypass line through the automatic bypass, it is connected
directly to the mains supply and is therefore no longer protected against main faults.
Maintenance Bypass
A second bypass circuit contained in the UPS cabinet, identified as the ‘Maintenance Bypass’ line is included to enable
the reserve supply to be made available to the load while facilitating a safe working environment for carrying out
scheduled UPS system maintenance or trouble shooting. The circuit is manually selected by the Manual Bypass Switch
(3) which can be padlocked in the OFF position.
WARNING
CAUTION: If an automatic circuit breaker device is not present in the input distribution panel, there remains a
dangerous voltage at the output terminals and also on the input terminals of the UPS module that is switched off.
Note: The load is not protected from main aberrations when operating on the maintenance bypass mode .