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Operation Overview 19
2
Operation Overview
Introduction
The Electronic Load is used for design, manufacturing, and evaluation of dc power supplies, batteries, and power
components. The primary operating features of the Electronic Load are: constant current (CC) mode, constant voltage (CV)
mode, or constant resistance (CR) mode. The input can also be turned on or off (open circuit) or short circuited.
Other features include a built-in GPIB interface and a built-in pulse generator. Pulse mode allows dynamic testing of power
supplies and components, without giving the device under test time to heat up. This flexible mode provides three triggering
methods, allowing synchronization with a wide variety of events. A Save/Recall feature allows you to save up to 7 complete
instrument setups, one of which can be saved in non-volatile memory so that it is recalled automatically at power-on. Also
standard is GPIB readback of actual input voltage and current, and extensive protection and status reporting capability.
The Electronic Load contains a fan whose speed automatically increases or decreases as the heatsink temperature rises and
falls. This reduces the overall noise level because the fan does not run at maximum speed at all times.
The input power rating curve for the Electronic Load is shown in Table 1-1. Refer to the extended power paragraphs in this
section for a description of the power rating curves. Note that regardless of the power rating, input current is derated
linearly from 2 volts down to 0 volts.
If your application requires a greater power or current capacity than one Electronic Load can provide, Electronic Loads can
be connected in parallel in CC or CR mode.
Front Panel Description
The front panel includes a 12-character alphanumeric display, 11 status indicators, and three groups of keypads. Ordinarily
the alphanumeric display shows the input voltage and current. By using the
key you can sequentially display input
power, programming error codes, and protection-circuit status. If any protection circuits are active, that status will be
displayed first when you use the
key. The alphanumeric display shows what function is being performed when
you use the keypads.
The display also includes 11 annunciators that point to the 11 status labels printed on the front panel. These are: Constant
Current, Constant Resistance, Constant Voltage, Transient, Unregulated, Protection, Error, Shift, Remote, Address, and
Service ReQuest.
Three keys perform two functions, with the alternative function labeled in blue above the key. The alternative function is
selected by first pressing the blue (shift) key, which turns on the Shift annunciator and enables the alternative function.
Remote Programming
Commands sent to the Electronic Load via GPIB are decoded by the primary microprocessor, which detects syntax and
range errors. The primary processor also prescales data and maintains the status registers. Three commands have aliases
for compatibility with other HPSL instruments. MODE can also be called FUNCtion, INPut can also be called OUTPut,
and INSTrument can also be called CHANnel . OUTPut and INSTrument would typically be used if you want your
program to refer to the Electronic Load in terms of the device or instrument under test. When using the CHANnel
command, remember that the Electronic Load is always channel 1.