Agilent Technologies 6626A, 6628A, 6625A, 6629A manual Local Control Of System Functions

Setting Overvoltage Protection

Programmable overvoltage protection (OVP) guards your load against overvoltage by crowbarring and downprogramming the power supply output if the programmed overvoltage setting is exceeded.

A fixed OV circuit with a trip level about 20 percent above the maximum programmable voltage acts as a backup to the programmable OVP. When overvoltage protection is activated, the output is shorted and the message ’’OVERVOLTAGE’’ will appear on the front panel display.

The selected output’s overvoltage setting is programmed locally using the OVSET key. For example, program the overvoltage to 10.5 volts by pressing:

OVSET 1

Resetting Overvoltage Protection

0

.

5

ENTER

The condition that caused the OVP must first be cleared and then the output can be returned to its previous state by pressing the RESET key.

Enabling/Disabling Overcurrent Protection

The overcurrent protection feature guards against excessive output currents. When the output goes into the + CC mode and OCP is enabled, the OCP circuit is activated which downprograms the output voltage and disables the output. For this condition, the message ’’OVERCURRENT’’ appears on the front panel display.

The selected output’s overcurrent protection feature can be turned on and off from the front panel. The OCP key toggles the selected output’s overcurrent protection circuit on and off. When it is on (enabled), the OCP ENBLD annunciator will be on.

Resetting Overcurrent Protection

The condition that activated the OCP circuit must first be cleared and then the output can be returned to its previous state by pressing the RESET key.

Local Control Of System Functions

The System Function keys consist of the ADDR, ERR, STO, and RCL keys as shown in Figure 6-1. These keys are independent of the output selected and are used in setting the supply’s GP-IB address, displaying error messages, and storing/recalling voltage and current settings for all of the supply’s output channels.

Setting the Supply’s GP-IB Address

As described in page 40, before you can operate the supply remotely, you must know its GP-IB address. You can find this out locally from the front panel by pressing:

ADDR

The supply’s present address will appear in the display. Address 5 is the factory set address.

If you want to leave the address set at 5, you can return to the metering mode by pressing the METER key or you can press another function key.

If you want to change the address, you can enter a new value.

Any integer from 0 through 30 can be selected.

88Local Operation