Software
Figure 17 – Screen Shot of PWRVIEW Measure Form
Like many other test instruments connected to a PC such as oscilloscopes and function generators VISA is used as the transparent connection mechanism between PA1000 and the PC workstation. VISA is an acronym for Virtual Instrument Software Architecture that provides application independence from the test instrument connection medium by providing a standardised access protocol to test instrumentation. Like a networking protocol VISA each test instrument has its own unique address and has spy programs available to view VISA messages for diagnostic purposes.
VISA supports physical mediums such as GPIB, USB and Ethernet. Interestingly the PA1000 Ethernet interface does not use VISA but a direct connection to the PWRVIEW application.
I won’t delve too far into this subject but suffice it to say that at least two existing versions of VISA; NI-VISA from National Instruments and TEKVISA from Tektronix. They are aware of each other and can co-exist on the same machine but can complicate matters. In fact the TEKVISA suite provides a Conflict Manager to cater for this circumstance and enables each instrument to be associated with the VISA environment of your choice. Disappointingly the TEKVISA needs to be disabled in order for the PWRVIEW application to work with the PA1000. Hopefully Tektronix will address this issue.
Figure 18 – Conflict Manager
Software Installation
The PA1000 software called PWRVIEW is downloadable from the Tektronix website. Two Windows versions are available – one for 32-bit and the other 64-bit. The installation executable attempts to check the presence of and install its required prerequisites prior to installing the PWRVIEW application. The prerequisites are NI-VISA version 5.1.1 and .NET Framework 4.0.
As much as one wants a seamless installation process the PWRVIEW for me wasn’t on both Windows 7 32-bit and 64-bit. When installation process detects its need for a prerequisite to be installed it launches the prerequisite’s installation program and then waits for its successful completion before proceeding to the next step. The prerequisites require a system reboot as a part of their installation process and although this type of activity is not unusual but for some reason after the mandatory system reboots the installation process attempt to resume but fail by halting with an error message. This is no show stopper because the installation process can be relaunched and the subsequent attempt detects the installation of any prerequisites and proceeds to the next step.
Figure 19 - The error screen when attempting to run 32-bit PWRVIEW on a 64-bit machine.
PWRVIEW Operation
Figure 20 - PA1000 Configuration Page
The PWRVIEW software is designed to remotely operate with the PA1000 and PA4000 range of Power Analysers. It has a Setup form that makes remote configuration straightforward. All of the parameters from the Power Analyser’s nested menu system are presented on a single form making for quick and easy configuration. Once the parameters have been set to your liking they can be uploaded into the Power Analyse with the press of the Upload button.
The Setup form also contains several Wizard options to assist with the DUT and test instrument connection and configuration of parameters. Attached are some sample screenshots to illustrate the point.
Figure 21 - LED Inverter Wizard
Figure 22 - Full Compliance Standby Wizard Page 1
Figure 23 - Full Compliance Standby Wizard Page 2
Like the original PA1000 firmware the current version of power view has not been completely converted across for Tektronix. Figure 22 shows a Voltech Breakout box rather than the Tektronix Breakout box.
Figure 24 – Waveform view.
The PWRVIEW graphs use continuous smooth lines and are much prettier than the graph display on the PA1000 and have the ability to be easily scaled or zoomed. Operation is straightforward once one understands that the Start button needs to be depressed to commence the desired activity. The scaling sliders are not necessarily linear. For the Power scale the slider is exponential.
Figure 25 – Current Harmonic Graph
There are quite a large range of forms and graphs and all are useful for diagnostic purposes. Pictured above is a Current harmonic graph of a Notebook SMPS (Switch Mode Power Supply) and from it one can see that it would not have great PF (Power Factor).
For development one would want to only have the fundamental frequency present. This alone is not enough to ensure a good PF. The current signal should be in phase with the input voltage. Details of this can be seen from the Waveform view where one can see the phase relationship between current and voltage. It can bee seen from Figure 24. that the current is in phase but the wave form is non-sinusoidal.
In addition to the local use of USB Memory Sticks on the PA1000 front panel PWRVIEW provides the convenience of direct logging onto disk. This can be useful depending when operating in a laboratory or workbench scenario. The data that has been logged to disk can be further processed or analysed as required.
The PA1000 Power Analyser its PWRVIEW application is a very convenient and powerful combination for those who deal with single phase power analysis. I'm sure that this product will contribute towards efficiency improvements for many future products.
