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
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.
Introduction to the Agilent 6800 AC Power Source/Analyzer 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.
Agilent 6800 Series Output Transients 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.
Model of the Transient System 5
Agilent 6800 Series Triggering 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.
Output Transient Trigger Model Measurement Trigger Model 7
Agilent 6800 Series Measurements 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.
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.
Applications The following section contains six application examples.
Application 1: Simulating AC Line Sub-Cycle Dropouts Overview of application Implementation details The ability of a switching power supply to maintain its output voltage setting in the presence of typical ac line disturbances is critical to its enduse. If the end-use of the power supply is installation into a computer, for example, sensitivity to ac line variations can result in unexpected loss of critical data and system downtime.
Upon the receipt of the trigger, the ac source continues to output a 120 Vrms, 60 Hz sinewave for 5 seconds. After the 5-second trigger delay, the rms voltage drops to 0 Vrms at 80° of the cycle and then rises back to 120 Vrms (0.001389 seconds later) at 110° of the cycle. Variations on this implementation 1. The Pulse width can be increased to simulate full cycle dropouts. 2. The Pulse count can be set to a value >1 and the Pulse period can be programmed to 0.
Application 2: Generating MIL-STD-704D Waveforms Overview of application Agilent 6800 series features used U.S. Military Standard 704D (September 30, 1980) establishes the requirements of electrical power transfer between the aircraft or ground support electrical system, and the electronic equipment utilizing this power on board the aircraft.
Agilent 6800 series setup (continued) • Set the List points as follows: List Point Vrms frequency Vrms Slew Dwell Time 1 115 V 400 Hz INF *60 s 2 127 V 400 Hz INF 0.01 s 3 88 V 400 Hz 566 V/s 0.07 s 4 115 V 400 Hz INF *60 s 5 57 V 400 Hz INF 0.01 s 6 76 V 400 Hz 283 V/s 0.
List Timing Diagram for Application 2 16
Application 3: Performing IEC 555-2 Measurements Overview of application Agilent 6800 series features used IEC 555-2 (1982) is a regulatory standard that pertains to ac line disturbances, namely current harmonics. These current harmonics are caused by connecting household appliances and similar electrical equipment to a 230 V, 50 Hz ac mains.
Agilent 6800 series setup • The ac source output is connected to the ac input of the equipment under test. • Set the output waveform to sine. • Set the rms voltage to Fixed mode. • Set the frequency to Fixed mode. • Set the voltage to 230 Vrms. • Set the frequency to 50 Hz. • Set the measurement window to Rectangular. • Enable the output of the ac power source/ analyzer. • Wait until the ac input to the equipment is in a steadystate condition.
Application 4: Performing Inrush Current Measurements Overview of application Switch mode power supplies are commonly used in many electronic products. These power supplies typically have input capacitors that cause high levels of peak inrush current to be drawn as they charge from the rectified line at turn-on. The peak amplitude of the inrush current varies with the turn-on phase of the ac voltage cycle. Usually, the highest peak inrush currents occur near the peak (90°) of the voltage cycle.
Agilent 6800 series setup • • • • • • • • • • • • • • Set the initial (immediate) voltage to 0 Vrms. Set the triggered voltage level to 120 Vrms. Set the frequency to 60 Hz. Set the peak current limit to maximum. Set the transient trigger source to BUS. Set the trigger synchronization source to Phase. Set the initial synchronization Phase to 40° (re-program to 50°, 60°, 70°, 80°, and 90°). Set the acquisition trigger source to TTLTrg. Set the data acquisition offset to -409 points.
Application 5: Generating User-Defined Waveforms Overview of application Agilent 6800 series features used The creation of user-defined waveforms is useful for simulating ac line disturbances that are unique to the operational environment of the device being tested, and then measuring that device’s susceptibility to the disturbance. This is the fundamental objective of environmental test standards that pertain to the ac line.
Agilent 6800 series setup • Connect the ac source output to the ac input of the equipment under test. • Use the computer to develop a 1024 point array representing a cycle of voltage amplitude data. • Use the TRACe:DEFine command to name the waveform CLASS 1 and allocate non-volatile storage space. • Use the TRACe:DATa command to send the 1024 point array to the ac power source/analyzer. • Set the Shape to List mode.
Application 6: Operating the Agilent 6812A and 6813A at Low Frequencies Overview of application Implementation details For some applications, such as the simulation of European railway power systems, a low frequency (16.6 Hz) ac waveform is required. Generating low frequency waveforms with ac sources can present testing challenges due to output power derating and programming inaccuracies, depending on the regulation technique used.
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