Xantrex ALM - REV A, Manual, Page: 24 / 36

©2001 Xantrex Technology Inc.
P/N 975-0027-01-01 Rev A 09/01
20
3.0 OPERATION
Active-Low Configurations
DC Load Controller
The ALM can also be configured to operate as a load controller to manage the
discharging of the inverter’s battery. (See Figure 3-6.) A load controller prevents
damage to the battery from over-discharge during periods of poor charging or
excessive loads. The ALM also can provide automatic reconnection of the loads at
the reconnect setting. Reconnection of the load is allowed once the battery voltage
has exceeded your reconnect setting. When used as a DC load controller, the user
adjustments, enabled by your inverter’s control device, control the reconnect and
disconnect settings.
+
-
BATTERY VOLTAGE IS WITHIN
ACCEPTABLE LIMITS
BATTERY VOLTAGE IS BELOW
ACCEPTABLE LIMITS
N.O.
N.C.
COM
ALM
120 VAC
Coil
N.O.
COM
External Power Relay
120 VAC
Coil
BATTERY BANK
+
-
External Power Relay
+
-
DC Load
N.C.
N.O.
COM
N.C.
DC Load
Communications
Cable
Inverter
AUX
N.C.
Communications
Cable
Inverter
AUX
BATTERY BANK
+
-
N.O.
COM
ALM J1 J1
Figure 3-6
Using the ALM as a DC Load Controller
Diversion Load Controller
Diversion load controllers (also known as wind or Hydro-Dump controllers)
operate by diverting excess charge current from the battery that is being charged to
another load, for example, power resistors, water heater, etc. (See Figure 3-7.) This
prevents damage to the charging source from an over-speed condition that could
occur if the charging source is suddenly disconnected from all loads. Even with a
solar-based system, it may be desirable to use this configuration to divert excess PV
power to operate DC loads.
When the ALM is configured this way, its setpoint would energize the relay to
energize a contactor (one that could handle the excess current). This would allow
the excess charge current to divert to the “dump load” thereby preventing
overcharged batteries.
CAUTION: If you are using AC loads as your diversion
load through the inverter, be aware that you may
overcharge your battery if the inverter fails or is
turned OFF.