Agilent Technologies 66001A - Manual (Page 23)

Installation 23
Output Rating
The rated output voltage and current specified in Table 1-1 applies at the output terminals of the power module. With
remote sensing, the power module must increase its output to compensate for voltage dropped in the load leads. If you
attempt to provide full rated output voltage at the sense terminals (load), the power module’s output voltage may exceed its
maximum rating. This may trip the OV protection circuit, which senses the voltage at the output terminals, or cause an
unregulated output condition, particularly when the ac line voltage is low.
Output Noise
Noise picked up by the sense leads may appear at the output of the power module and can adversely affect the load
regulation. To minimize noise pickup, twist the sense leads and route them parallel and close to the load leads. It may be
necessary to use shielded sense leads in noisy environments. If you do, ground the shield only at the output connector
ground screw. Do not use the shield as one of the sense leads.
Parallel Operation
Power modules may be connected in parallel to obtain increased output current. The power modules must be individually
programmed; they do not function in the autoparallel mode that is commonly used by many Agilent power supplies.
Figure 2-5 shows two power modules connected in parallel. You must keep the same impedance to the load by using leads
of equal length and wire size from each module to the load. Select one module (usually the one with the lesser current
capacity) to operate in the "CV Mode". The other module then must operate in the "CC Mode" module. If you are using
remote sensing, connect the sense leads to the module operating in the CV mode.
Since you must program one module to operate in CV mode and the other to operate in CC mode, refer to the output
characteristic curve shown at the end of Chapter 1 to see what this means. Curve
 shows a module operating in CV mode;
its output voltage remains constant over the range of its operating current. Curve
ô shows a module operating in CC mode;
its output current remains constant over the range of its operating voltage.
Figure 2-5. Connecting Power Modules in Parallel
For proper parallel operation, observe the following rules:
1. Program both module outputs OFF.
2. Program the CV mode module for the desired output voltage.
3. Program the CV mode module’s OVP voltage to the desired value; always higher than the output voltage.
4. Program the output and OVP voltages of the CC module slightly higher (about 1 volt) than those of the CV module.
This is to ensure that the CC module stays in CC mode.