that the current limit value can be set from zero to maximum rated value.
OPERATING MODES
The setting of the rear panel switch determines the operating modes of the power supply. The local operating mode is set so the power supply senses the output voltage directly at the output terminals (local sensing) for operation using the front panel con- trols (local programming). Other operating modes are: remote voltage sensing and remote programming of output voltage and current using external voltages.
LOCAL OPERATING MODE
The power supply is shipped from the factory configured in the local operating mode. Local operating mode requires the switch settings of the rear panel, as shown in Figure 4. The power sup- ply provides constant voltage(CV) or constant current(CC) output.
Constant Voltage Operaton
To set up a power supply for constant voltage operation, proceed as follows:
a.Turn on the power supply and adjust
b.While depressing DISPLAY OVP/CC SET switch, adjust 10- turn CURRENT control for the desired current limit.
c.With power off connect the load to the output terminals.
d.Turn on the power supply. Verify that CV LED is lighted. During actual operation, if a load change causes the current limit to be exceeded, the power supply will automatically cross over to constant current mode and the output voltage will drop proportionately.
Constant Current Operation
To set up a power supply for constant current operation, proceed as follows:
a.Turn on power supply.
b.While depressing DISPLAY OVP/CC SET switch, adjust CURRENT control for the desired output current.
c.Turn up the VOLTAGE control to the desired voltage limit.
d.With power off connect the load to the output terminal.
e.Turn on power supply and then verify that CC LED is lighted. (If CV LED is lighted, choose a higher voltage limit. A voltage setting that is greater than the current setting multiplied by the load resistance in ohms is required for CC operation.) During actual operation, if a load change causes the voltage limit to be exceeded, the power supply will automatically cross over to constant voltage operation at the preset voltage limit and output current will drop proportionately.
Overvoltage Protection (OVP)
Adjustable overvoltage protection guards your load against over- voltage. When the voltage at the output terminals increases (or is increased by an external source) to the OVP shutdown voltage as set by the OVP ADJUST control, the supply's OVP circuit dis- ables the output causing the output voltage and current to drop to zero. During OVP shutdown the OVP LED lights.
False OVP shutdowns may occur if you set the OVP shutdown too close to the supply's operating voltage. Set the OVP shut- down voltage 4% of output +2.0 V or more above the output volt- age to avoid false shutdowns from
Adjusting OVP. Follow this procedure to adjust the OVP shut- down voltage.
a.With the VOLTAGE control fully counter clockwise, turn on the power supply.
b.While depressing DISPLAY OVP/CC SET switch, adjust the OVP Adjust control to the desired OVP shutdown using a small,
c.Follow the procedure for CC or CV operaton to set the out- put voltage and current
Resetting OVP. If OVP shutdown occurs, reset the supply by turning power off. Wait one or more seconds, and turn power on again. If OVP shutdown continue to occur, check the connections to the load and sense terminals, and check the OVP limit setting..
Strong electrostatic discharge to power supply can make OVP trip and eventually crowbar the output, which can effectively protect output loads from the hazardous ESD current.
CONNECTING LOADS
The output of the supply is isolated from earth ground. Either out- put terminal may be grounded or the output can be floated up to 240 volts off ground. Total output voltage to ground must not exceed 240 Vdc.
Each load should be connected to the power supply output terminals using separate pairs of connecting wires. This will minimize mutual coupling effects between loads and will retain full advantage of the low output impedance of the power supply. Each pair of connecting wires should be as short as possible and twisted or shielded to reduce noise
If load considerations require that the output power distribution terminals be remotely located from the power supply, then the power supply output terminals should be connected to the remote distribution terminals via a pair of twisted or shielded wires and each load separately connected to the remote distribution termi- nals. For this case, remote sensing should be used (See para- graph "Remote Voltage Sensing").
OPERATION BEYOND RATED OUTPUT
The output controls can adjust the voltage or current to values up to 5% over the rated output. Although the supply can be operated in the 5% overrange region without being damaged, it can not be guaranteed to meet all of its performance specifications in this region.