QTech Data Systems DNP3 RTU - Manual (Page 29)

DATRAN XL4 RTU – Owners Manual – v1.1 June 2012
www.qtech.co.nz Page 29
POWER SUPPLY POWER SUPPLY POWER SUPPLY POWER SUPPLY
This section describes the power supply and connection of the XL4 RTU.
Connections Connections Connections Connections
The XL4 RTU is designed to operate with DC power supply voltages of nominally 12 or 24V but can operate on any
DC voltage within the range 11 to 28 volts. The XL4 RTU draws approximately 200mA at 12V and 100mA at 24V.
The power connector is located on the bottom panel of the XL4 RTU and is labelled ‘PWR’. The connections to the
power connector are:
-V Ground. The negative lead of the power supply
+V Positive. The positive lead of the power supply
O/P The switched positive output to auxiliary equipment
Note The XL4 RTU has a 2 amp fuse on the Q22 I/O board to protect the unit under fault conditions or when
reversed polarity or over-voltage power supplies are connected to the module.
This 2 amp fuse limits the available switched positive output on the ‘+’ connectors to approximately 1.5
amps. The QTech part number for replacement fuses is FS-2AMPTES
The DC power supply to the XL4 RTU must be adequately smoothed and be free from noise and voltage
transients. Where the DC supply is derived from the AC mains, or batteries with an associated AC mains battery
charger these devices must comply with the relevant electrical regulations.
In many applications the XL4 RTU is operated from power supply systems with a 12V or 24V standby battery. In
the event of the main power supply failing and the standby battery becoming discharged the XL4 RTU has a low
battery detection circuit. This circuit turns off the internal power supply of the XL4 RTU to prevent erratic operation
of the Q22 Module and to prevent the battery from being totally discharged
The low battery detection modes voltages are:
12V Module OFF at 10.5 volts and back on at 11.5 volts.
24V Module OFF at 21.0 volts and back on at 23.0 volts.
The XL4 RTU also has an optional software controlled low battery alarm. This alarm turns on when the battery falls
below 11.5/23.0 volts and turns off again when the battery rises above 12.5/25 volts for 12/24 volts power supplies
respectively. These thresholds can be configured in the Battery tab of QTech Workbench.
The DC power supply to the module must be adequately smoothed and free from noise and voltage transients.
Where the DC supply is derived from the AC mains, or batteries with an associated AC mains battery charger these
devices must comply with the relevant electrical regulations.
Circuit details of Power Supply Front End.
In the above circuit diagram the 30 volt transient suppression diode ZD1 and the 2 amp fuse protect the Q22
Module against reversed supply connection, over voltage supply and transient voltages. The fuse is a plug-in 2