Alpha Technologies Cordex Controller Ver.3.1x - Manual (Page 10)

0700015-J0 Rev B 8
2.4 Mixed Rectifier System
All controllers, except the CXCU, allow one type of Alpha Pathfinder model rectifier to work in parallel with
one type of Alpha Cordex model rectifier, for example, a PFM 48V-10kW or PFM 48V-3kW with a CXRF
48-3.6kW. Another example is a PFM 24V-3kW with a CXRF 24-3.1kW. The load share of each rectifier is
based on the percentage of the maximum output current of the rectifier; see Rectifier Report (4.7.2).
The Pathfinder rectifiers are not shown under Upgrade Firmware as that submenu applies to Cordex
rectifiers and smart peripherals only.
2.5 Safe Voltage
The Safe Voltage is the voltage that the rectifiers default to if they lose communications with the controller.
The Supervisor can set the default system voltage (Safe Mode) that will be used if the communications to
the Cordex rectifiers fails. This feature has a time delay that varies according to the rectifier. Most rectifi-
ers will revert to Safe Mode after five (5) minutes. The rectifier manual lists the default parameters.
Note: In general, the open circuit voltage for VRLA batteries is determined to be a point where discharge
or over charge will not occur.
2.6 Power Save
The Power Save feature enables the Supervisor to improve operational efficiency by running only the
necessary number of rectifiers. For example, when the load is significantly less than the available system
power, the controller shuts down one or more of the rectifiers so that the remaining rectifiers operate with
greater efficiency at a higher current level. A short (one-minute) time delay or hysteresis is built in to avoid
nuisance alarms and to prevent changes if the load is fluctuating.
With Power Save, rectifier usage rotates on a weekly basis to share the service time. Power Save comes
into effect when a minimum discharge or load current (~2.5% of maximum current of one rectifier) is
achieved. Battery charge current limit calculations are based on the rectifiers that are running.
The Power Save feature is suspended during Battery Test mode. See 4.12.4.
NOTE: The Remote Shutdown setting must be enabled for the rectifier (see Rectifiers > Configure
Rectifiers) to operate in Power Save.
2.7 Auto DC Priority
The inverters can be configured to automatically switch to DC Priority mode when a custom alarm is acti-
vated. The alarm could be triggered by a digital input such as a signal from an alternative energy source
– a fuel cell for example that has just switched on.
When the custom alarm activates, the CXC automatically switches the Inverters to draw from DC power
as much as possible. When the alarm is deactivated, the command is sent to return to AC Priority. (Cus-
tom alarms are configured from Alarms-> Configure Alarms .)
For more information, see section 6.4.7.
2.8 Battery Temperature Compensation
The automatic battery temperature compensation feature (Temp Comp or TC) works with Cordex series
rectifiers that support CAN bus communications and Pathfinder series rectifiers that support RS-485
remote communications. Temp Comp may be active in either the Float (4.9) or Equalize (4.10) mode.
Temperature inputs are available on the CXC for monitoring a lead acid battery string. Temperature sen-
sor readings can be displayed on the GUI in either the Celsius (°C) or Fahrenheit (°F) scales.
The CXC has the flexibility to display the breakpoints in voltage and temperature. The breakpoints can be
entered as voltages or temperatures.
The detection of a thermal runaway is limited to a programmable Battery Over Temperature Alarm. The
Supervisor can select the temperature that triggers an alarm.