Agilent Technologies 6800 User Manual
Agilent 6800 Series
AC Power Source/Analyzer
Product Note
Using the Agilent Technologies 6800 Series
AC Power Source/Analyzers for Generation
and Measurement
Applications:
• Simulating AC Line Sub-Cycle Dropouts
• Generating MIL-STD-704D Waveforms
• Performing IEC 555-2 Measurements
• Performing Inrush Current Measurements
• Generating User-Defined Waveforms
• Operating the Agilent 6812A and 6813A
at Low Frequencies
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Introduction
This note provides information on how you can
use the features of the Agilent Technologies 6800
series ac power source/analyzers to address a
variety of applications. Although your exact application may not be listed here, the capabilities
described can be generalized and applied to your
specific needs. The programming examples are
given in QBASIC.
These are the capabilities that are discussed and
a description of how they can be applied:
Table of Contents
Introduction to the Agilent 6800 AC Power Source/Analyzer
Agilent 6800 Series Output Transients
Agilent 6800 Series Triggering
Agilent 6800 Series Measurements
Application 1: Simulating AC Line Sub-Cycle Dropouts
Application 2: Generating MIL-STD-704D Waveforms
Application 3: Performing IEC 555-2 Measurements
Application 4: Performing Inrush Current Measurements
Application 5: Generating User-Defined Waveforms
Application 6: Operating the Agilent 6812A and 6813A
at Low Frequencies
3
The 6800 series ac power source/analyzers are
members of the Agilent Technologies “One-Box”
Solution power products family. These products
offer an integrated solution for ac power testing
applications.
The 6800 series combines the functionality of the
following instruments in one box:
• power amplifier
• arbitrary waveform generator
• power analyzer
• harmonic analyzer
• waveform digitizer
The power amplifier and arbitrary waveform
generator capabilities produce waveforms with
programmable amplitude, frequency, and waveshape. Each model has pre-programmed sine,
square, and clipped sine waveshapes. For added
flexibility, twelve user-defined waveforms can
be created and stored in non-volatile memory.
Waveforms can be programmed using the 6800
series transient generation system to simulate
sophisticated and repeatable ac line disturbances
or output sequences.
The power analyzer and harmonic analyzer capabilities provide high precision measurements
including:
• rms, dc, ac+dc voltage and current
• peak voltage and current
• real, apparent, and reactive power
• harmonic analysis of voltage and current waveforms providing amplitude and phase up to the
50th harmonic
• total harmonic distortion
• triggered acquisition of digitized voltage and
current
The 6800 series can be used in bench or ATE applications. The fully featured front panel and built-in
GPIB and RS-232 interfaces allow you to program
waveforms, measure parameters, and monitor the
status of the ac power source/analyzer.
Each model features a SCPI (Standard Commands
for Programmable Instruments) command set. This
industry standard command set simplifies test system development by offering command set commonality between all types of instrumentation. Instruments performing the same function use the same
self-documenting SCPI instructions. For example,
the same commands are used to program a waveshape on the 6800 series ac power source/analyzers
as on a function generator. Because you spend less
time learning device commands, you can get your
application up and running faster.
The following sections of this product note explain
how to optimize your usage of the features of the
6800 series products. At the end of this product
note there are practical examples that show how
these features can be applied.
Introduction to the Agilent 6800 AC Power Source/Analyzer
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A programmable output value of the ac power
source/analyzer can operate in one of four modes:
FIXED, Step, Pulse, or List. The default setting is
FIXED mode, where the output will stay “fixed” at
the programmed value until another command is
sent to change it. The remaining three operating
modes constitute the Transient Subsystem. Output
transients are used to:
• synchronize output changes with a particular
phase of the voltage waveform
• synchronize output changes with trigger signals
• simulate ac line disturbances with precise duration and phase control
• create sequences of output changes
Output transients are triggered actions and will
cause the output of the ac power source/analyzer
to react in a manner defined by the selected mode.
What Programmable Functions can be
Controlled by the Transient Subsystem?
The 6800 series provides control of many output
parameters. Most of these can be programmed as
an output transient. The following output parameters are subject to transient control:
• ac output voltage
• dc output voltage (Agilent 6812A and 6813A only)
• frequency
• phase (Agilent 6834A only)
• waveform shape
• ac voltage slew rate
• dc voltage slew rate (6812A and 6813A only)
• frequency slew rate
• peak current limit (6812A and 6813A only)
• rms current limit
• dwell time (List mode only)
Upon receipt of a trigger, an output parameter set
to Step, Pulse, or List mode will transition from an
immediate level (its initial output setting) to one or
more levels (successive output settings). The number of successive output settings is, in part, what
differentiates one transient mode from another.
What is a STEP Transient?
A Step transient generates a single triggered output change (from an immediate output level to
ONE successive output level) of one or more of the
output parameters subject to transient control.
Only output parameters programmed to Step mode
will be part of the triggered action. The output
will remain at the final output level once the Step
transient is complete.
What is a PULSE Transient?
A Pulse transient generates a triggered output
change that returns to its immediate output level
after a programmed time period. A Pulse transient
can also be programmed to repeat the output
change more than once or continuously.
What is a LIST Transient?
A List transient generates a sequence of output
changes. Each output change of the sequence is
called a List point. All parameters subject to transient control can be programmed at each List point.
A List can contain up to one hundred points. The
list of points can be programmed to execute once
or to repeat from one to an infinite number of times.
Agilent’s 6800 series List points can be paced by
external triggers. When paced by triggers, the output will remain at a particular List point until a
trigger is received. Only then will it proceed to the
next programmed point.
List points can also be paced by individual programmable dwell time parameters associated with
every point. Only when the dwell time for a particular List point expires will it proceed to the next
List point.
Once the List is completed, the output returns to
the immediate levels.
Agilent 6800 Series Output Transients
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Model of the Transient System
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In ATE applications, triggers are often a convenient way of synchronizing test system events and
increasing test throughput. These benefits also
apply to the triggering subsystems in the 6800
series products since these products combine the
capabilities of many test instruments. Each model
is equipped with the ability to send and receive
triggers, and to perform or initiate a multitude of
synchronized functions upon receiving a trigger.
Triggers can be used to change the output, synchronize a change to a phase of a waveform cycle,
and synchronize a measurement to an output
change. The effectiveness of the triggering capability
can be shown when measuring worst case inrush
current of a switching power supply. Using the
6800 series triggering subsystem, the output can
be triggered to turn on at a phase near the peak
of the ac cycle for simulating a worst case ac line
condition. Simultaneously, the ac source can be
triggered to take current measurements to characterize the behavior of the power supply under test.
In addition, triggering can be extended to external
test equipment via the Trigger Out connection.
The 6800 series has two main triggering subsystems,
one for generating transients and one for making
measurements. These two subsystems have common
trigger sources that can synchronize transient and
measurement events.
What Actions Can be Triggered?
The following actions of the 6800 series can be
triggered:
• a change in output setting
• the start of a Step, Pulse, or List transient
• the pace of a List sequence
• the acquisition of digitized voltage and current
• the synchronization of an output change to
a phase of the cycle
A programmable time delay can be specified for
triggers that generate output changes. This allows
the insertion of a specified time delay between
the receipt of the trigger and the action of the
ac power source/analyzer output.
What Can Serve as the Source of the Trigger?
The 6800 series can receive triggers from the
following sources:
The GPIB. The computer can send trigger commands
to the ac power source/analyzer. There is a short
command processing time associated with this
source.
External Trigger In. This is the 6800 series TRIGGER
IN connector. It accepts TTL levels, with the falling
edge detected as the trigger.
TTL Trigger. The TTL trigger is an internal trigger
that causes the acquisition of digitized voltage and
current data.
This internal trigger can be generated when an
output transient begins or ends, or as the result
of List step execution.
How Can Triggers be Generated?
The 6800 series can generate a trigger on the
TRIGGER OUT connector as a result of the following actions:
• the beginning of a Step, Pulse, or List output
transient
• the completion of a Step or Pulse output
transient
• the completion of a List sequence
• the beginning of a List step
The TRIGGER OUT signal is a nominal
10-microsecond low-true pulse.
How Can the Agilent 6800 Series be Enabled
to Respond to a Trigger?
The default state of the ac power source/analyzer
is the idle state where trigger detection is disabled.
To respond to a trigger, it must be placed in the
“initiated state.” This can be done via the front
panel or over the bus. Once initiated, the ac power
source/analyzer can detect a trigger from the
selected source.
When the trigger is detected, the ac power source/
analyzer will perform the trigger action after waiting any programmed trigger delay time. Upon completion of the trigger action, the ac power source/
analyzer will return to the idle state.
Agilent 6800 Series Triggering
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Output Transient Trigger Model
Measurement Trigger Model
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The built-in power analyzer capability offers many
voltage, current, and power measurements to the
user. While on, the ac power source/analyzers are
continuously sampling instantaneous output voltage and current for several output cycles and writing the data to buffers. Each buffer, one for voltage
and one for current, holds 4096 data points. The
voltage and current data is used to calculate the
requested measurement parameter. There are two
basic methods to obtain a measurement: using the
MEASure command or the FETCh command. These
commands can return a single measured parameter,
an array of voltage and current harmonic data, or
an array of the 4096 voltage or current data values.
What is a MEASure Command?
When this command is sent to the 6800 series
ac power source/analyzer, the unit begins acquiring new voltage and current data into its data
buffers. Upon completing the acquisition of 4096
data points for voltage and current, the unit then
performs the required calculation to return the
requested measurement parameter. When a new
acquisition of instantaneous output voltage and
current data is desired, this command should be
used to return the requested measurement.
What is a FETCh Command?
This command allows the user to retrieve measured parameters from previously acquired voltage
and current data. For example, the FETCh command can be used after a MEASure command to
return calculated parameters from the same 4096
data points that were acquired by the MEASure
command. In addition, the FETCh command can
be used to retrieve measurement information after
triggering an acquisition of digitized voltage and
current data. This method provides the flexibility
to synchronize the data acquisition with a triggered
event, and then return many calculations from
the existing voltage and current data buffers.
Agilent 6800 Series Measurements
Pre-event and Post-event Acquisition Triggering
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How Can the Acquisition of Voltage and Current
Data be Controlled?
Two characteristics of the voltage and current
acquisition can be controlled: the sample rate,
and the beginning of acquisition relative to the
trigger. The ac power source/analyzer has a sample
rate of approximately 40 kHz (a sample every 25
microseconds) as the default setting. This means
it takes approximately 100 milliseconds for the
data buffers to fill with voltage and current data
points. The sample period can be programmed
from a minimum of 25 microseconds to a maximum of 250 microseconds (at 25-microsecond
increments).
The acquisition of voltage and current data can
also be initiated relative to the acquisition trigger,
thereby enabling the capture of pre-event and
post-event data. To capture pre-event or post-event
voltage and current data, the offset of data points
relative to the trigger is programmed. The range
of offset that can be programmed is from -4096 to
2xl0
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points. If the offset is negative, the values at
the beginning of the data buffer represent samples
taken prior to the trigger. If the offset value is zero
(the default setting), all data is acquired directly
after the trigger. If the offset value is positive, the
acquisition of valid buffer data will be delayed
from the receipt of the trigger.
MEASure and FETCh Command Execution Diagram
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