The typical voltages that the Lite-Minder charger would float the batteries are:
10 Deg. C
27.60 VDC
15 Deg. C
27.48 VDC
20 Deg. C
27.36 VDC
25 Deg. C
27.24 VDC
30 Deg. C
27.12 VDC
35 Deg. C
27.00 VDC
40 Deg. C
26.88 VDC
Above 40 deg. Centigrade no additional compensation is performed.
9.3
Switched Output
The Switched Output is an output that can be switched on and off and is controlled by an
external voltage applied to the Switched Command Signal Input. The designed function is to
act as an interface to energy saving controls such as time clocks, daylight harvesting, photo-
sensors or any building occupation sensing. It is also tied in to the VTD function so if the VTD
is desired for normally off loads, connect these loads to the Switched Output.
The Switched Output can be energized while in the Battery Charging mode of operation by
applying 120 or 277 VAC to the Maintained Enable Input.
When the Lite-Minder changes mode of operation to the Battery Power mode, the Switched
Output will automatically energize.
9.4
Battery Power Mode
Battery Power Mode can have several other names such as Emergency Power and Inverter
Mode. This terminology may be used throughout this document.
During Battery Power mode, the inverter is producing a pure sine wave for the output loads
and the batteries are being discharged. The output current is limited by an active pulse by
pulse current limit technique and limits the inverter from failure. The current limit is set to the
crest factor value or 4 times the average output current.
In the event of an overload there are several ways that the inverter will protect itself. First is the
pulse by pulse limit and second is by average sensing. The pulse by pulse is a transient
protection and occurs in the micro-second time scale, the average sensing looks at a heavily
filtered signal and occurs in the seconds time scale.
Since the crest factor is very high on the Lite-Minder, loads that have high inrush currents are
quickly up and running. This is very beneficial with normally off loads which seem to be more
prevalent with modern lighting and green building design techniques.
Transfer time between Battery Charge Mode and Battery Power mode occurs at two different
speeds. Since the Lite-Minder is a line interactive inverter, it senses the utility power and
transfers when it thinks that the utility has failed. This analysis sometimes causes transfers
when in actuality no power is lost and only a transient occurred from the incoming utility. The
two different speeds of Fast Transfer and Slow Transfer are important for different applications.
Pg. 21
