Agilent Technologies E3614A Service Manual download pdf (Page 10)

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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 10-turn VOLTAGE con-

trol for desired output voltage (output terminals open).

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 load-induced transients.

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, flat-blade screwdriver.

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 pick-up. (If a shield is used, connect one end to the

power supply ground terminal and leave the other end unconnec-

ted.)

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.

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Agilent Technologies E3614A Service Manual Page 10

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Agilent Technologies E3614A Service Manual Page 10

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