Appendix F: Forced Load Sharing; System Requirements - HindlePower AT30 SERIES Operating And Service Instructions

APPENDIX F
ONLINE SUPPLEMENT
INTRODUCTION
Multiple battery chargers are sometimes employed in dc power systems to provide
redundancy. Two or more chargers of the same voltage rating can be connected in parallel, each of
them capable of powering the connected dc load and charging the battery. If a battery charger
should fail during normal operation, the parallel charger can continue to supply the entire required
dc load current, and maintain charge on the battery.
When two (2) AT30s operate in parallel, they normally will not share the load current
equally. Since any two chargers will have slightly different characteristics, one of the two chargers
in a system will have a slightly higher dc output voltage, and will therefore assume more of the
burden of providing necessary load current. This section describes an optional accessory for the
AT30 which forces units to share dc load equally. The accessory (ordering p/n EJ5126-##) consists
of an interconnecting cable to provide such communication, and operating instructions.

SYSTEM REQUIREMENTS

•
The forced load sharing feature is designed only to work with two (2) AT30 Series battery
chargers. You cannot force load sharing with three (3) or more AT30s.
•
Both AT30s must have the same dc voltage & current rating, and have the same dc filtering.
•
Both AT30s must have the same ac input source and the same phase rotation.
•
Both AT30s must feature Rev. 6 (or higher) builds of the Main Control PC Boards (A1), and
corresponding (Rev. 6 or higher) software programs.
•
Both AT30s must use the same the same program version, since the forced load sharing option
has not been tested using different program versions in each unit. To view the program version,
press the LAMP TEST button on the front instrument panel of the AT30. When you release the
button, the front panel meter displays the version number for two (2) seconds.
•
The interconnecting signal cable length should be no more than 50ft (15m).
INSTALLING THE INTERCONNECTION CABLE
The AT Series forced load sharing accessory is normally supplied by the factory with a
standard 15ft (4.6m) interconnection cable). A 25ft (7.6m) long cable and a 50ft (15.2m) long cable
are also available. The interconnection cable is terminated at each end with a 6-pin connector that
mates with the plastic connector (J4) on lower-right corner of the Main Control PC Board (A1). One
end of the cable features an extra jumper in the connector, and should be identified for use with the
Secondary charger. The other end of the cable connects to the Primary charger. Either AT30 may
be selected as Primary or Secondary, but you may wish to choose the unit that is more accessible to
be the Primary. The Primary charger controls the dc output voltage of both AT30s.
You may run the interconnection cable through conduit if necessary. However, do not run
the cable through the same conduit with power wiring. Do not remove the connectors in order to
"fish" the cable through the conduit. Maximum pulling tension is 46 lb. (20.9kg). The cable has a
plenum-rated outer jacket, and passes the NFPA 262 flame propagation test. Install the cable
between the AT30s, and anchor it in place at both ends before connecting. Connect each end to the
Main Control PC Boards (A1), inserting the connector into J4 until it is completely seated.
Power cabling for the battery charger, battery, and dc load interconnection is not supplied
with the AT30 or the AT Series Forced Load sharing option. All user-supplied system wiring
should meet National Electric Code (NEC) standards, as well as local/site codes. Confirm polarity
of all dc cabling before making connections.
92
FORCED LOAD SHARING
http://www.ATSeries.net/PDFs/JA5054-00.pdf
NOTICE