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CONNECTION AND OPERATION
WARNING ! The unit has been pre-set to operate from an input voltage of 120 VAC.
Hence, before plugging the unit to the AC outlet, please ensure that the local AC power
supply voltage is 120 VAC. Operation from 230 VAC is possible by changing internal
settings. Please see details on page 3 under "OPERATION FROM AC INPUT VOLTAGE OF
230 VAC"
NOTE: The DC output connectors (RED + and Black -) have a tubular hole of diameter
0.2" (5mm) with a set screw. If bare wire with stranded conductors is used to connect
the load to the above output connectors of the power supply, the strands will spread out
as the set screw is tightened and hence, the set screw will not pinch all the strands. As
a result, the effective cross section of the current conducting area of the wire will be
reduced resulting in voltage drop at the load end, reduced efficiency and also overheat-
ing. For a firm connection, crimp / solder a suitable pin type of copper terminal on the
wire end to be connected to the power supply. For convenience, a pair of terminals
has been provided for crimping / soldering to the wire end.
OPERATION
- Ensure that the on / off switch on the power supply is switched off and it is
un-plugged from the AC outlet
- Switch off the 12 V load to be connected to the power supply. Connect the
positive input wire of the load to the RED (Positive) terminal of the power supply and the
negative input wire of the load to the BLACK (Negative) terminal of the power supply.
Ensure that the connections are secure and tight
- Plug the power supply into the AC outlet. Press the On / Off switch of the
power supply to the On position and check that the switch is illuminated indicating
availability of the AC input power. If the On / Off switch is not illuminated, recheck the AC
input connection, AC outlet and the fuse inside the power supply.
- The voltmeter on SEC-1235M will read 13.8 V.
- Now switch on the DC load
- The ammeter on SEC-1235M will indicate the current drawn by the load
- Ensure that the continuous load is limited to 30 A
COOLING FAN CONTROL / THERMAL PROTECTION
WARNING! Operate the unit in a well ventilated, open and cool area. Do not
block the openings at the fan discharge on the bottom of the unit and the
suction openings on the sides.
The units are cooled by convection and by forced air cooling. A temperature
controlled fan has been provided to improve cooling at higher loads and at
higher ambient temperatures. The switching on of the fan is controlled by a
sensor mounted on the power transformer. The fan will be switched on when
the temperature of the sensor reaches 60° C +/- 5° C. The fan will be automati-
cally switched off when the sensor cools down to 50° C +/- 5° C. Thus, at lower
loads or during lower ambient temperatures, the fan may remain switched
off.
An additional protection is provided to shut down the power supply in case the
fan fails or if the air flow is blocked or if the ambient temperature is very high. A
second temperature sensor is also mounted on the power transformer and will
activate at 105° C +/- 5° C and shut down the output of the power supply. After
the power supply cools down to 95° C +/- 5° C, the temperature sensor will de-
activate and the power supply will resume operation automatically
4.
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