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Tektronix TPS2000 Series Digital Storage Oscilloscopes . . . the first four-channel-isolated, batterypowered oscilloscopes that are equally at home in the lab or in the field. T ektronix continues to expand its range of “¼-VGA” liquid crystal display DSOs with three new models targeting the industrial power sector. The TPS2012 and TPS2014 models have a bandwidth of 100MHz (1GS/s), whereas the TPS2024 doubles that at 200MHz (2GS/s). Four fully-isolated measurement channels are provided on the latter two models, whereas the lower-cost TPS2012 has only two channels. Other common specifications include a vertical resolution of eight bits, a maximum sensitivity of 2mV/ div and a record length of 2.5K points. As reported in our earlier reviews We used the Tektronix A621 Current Probe for our power measurements. This little beauty can handle up to 1000A. 40  Silicon Chip (July 2001 and July 2002) of Tektronix DSOs, the company has succeeded in packaging their fully featured scopes into an amazing “shoebox” form factor, measuring just 336W x 161H x 130D and weighing in at only 3.2kg. This time around, they’ve even found space for two battery packs but more on that later. These scopes are exceptionally easy to use. Most-used functions such as horizontal and vertical scaling and trace position are instantly accessible using traditional analog-style knobs. Less-used functions are accessed with pushbuttons and simple on-screen menus. In fact, most users won’t need a manual to drive any of Tek’s DSOs. Nevertheless, context-sensitive, onscreen help is available at any time simply by pressing the “help” button. peak and cycle RMS are all built in, improving the usefulness of the instrument and easing the strain on the grey matter. A Fast Fourier Transform (FFT) maths function is also provided as standard on all three models. Hanning, Flat Top and Rectangular window types are supported, spanning 2048 sample points. Yet another useful feature in these instruments is their ability to capture glitches and edge anomalies that would not normally be detected with traditional sampling techniques. Tektronix call this digital real-time (DRT) sampling technology and it’s available on all four channels simultaneously. Familiar features Full isolation Not surprisingly, all of the features that made the earlier models a pleasure to use are included on these models as well. For example, pressing the “Autoset” button performs an instant setup, automatically dialling in the horizontal, vertical and trigger settings for each channel. Eleven commonly used waveform measurements, including period, frequency, rise and fall times, peak-to- Each measurement channel is isolated from all others as well as the chassis and mains power supply. The buzz word is “IsolatedChannel” technology and it provides a perfect solution for both grounded and floating high-voltage measurements in three-phase power and other circuits with different ground references. Up to 30V RMS floating can be measured when using the standard siliconchip.com.au Tektronix TPS2000 The New Isolated Channel Battery Operated Scope. P2220 passive probes. When equipped with the P5120 passive high-voltage probe (optional), the TPS2000 Series measures up to 1000V RMS (CAT II) from the probe tip to earth ground and floating voltages up to 600V RMS (CAT II, 300V RMS CAT III) on all channels simultaneously. Safe solution The channel isolation offered in these models is unique in a combined bench-top and portable instrument. Readers familiar with the challenges of measuring circuits that Do you face these Power Measurement Challenges? • Make multi-channel floating measurements • Measure current and voltage distortion and their spectral content • Measure harmonics, instantaneous power, power factor, switching loss to characterise power electronics circuitry • Measure 3-phase currents & voltages • Validate compliance to regulatory standards • Work in an environment without AC Power • Document and Save your measurement results For more information about the TPS2000 family... Talk to NewTek Instruments: Ph: 02 9888 0100 email: info<at>newtekinstruments.com NewTek Instruments Pty Ltd - Sydney - Melbourne www.newtekinstruments.com Fig.1: up to the 50th harmonic, along with THD, individual harmonic levels display, individual harmonic phase to fundamental and RMS values are all calculated for you by the Harmonics function. siliconchip.com.au January 2005  41 Fig.2: the optional power measurement and analysis software allows you to make accurate power measurements at the touch of a button, eliminating the need for manual calculations. In this example, the Waveform Analysis function displays basic but useful information at a glance. are not referenced to mains earth will immediately recognise the benefits. A method sometimes used when measuring such circuits with a benchtop scope is to disconnect mains earth from the instrument, so “floating” it above ground. This method has two serious side effects. First, it means that the entire chassis of the scope is at the same potential as the equipment under test. Even if the equipment is deemed Fig.3: the Power Analysis function takes voltage and current measurements from two channels and displays true and reactive power, power factor and phase angle. Here, the top two traces show voltage and current in the circuit under test, whereas the bottom trace is generated by the function itself and represents instantaneous power. low voltage and therefore “safe”, a primary to secondary breakdown could expose the user to life-threatening voltages. Second, mains-powered scopes exhibit high parasitic inductance and capacitance when floated, which distorts signal measurements. By contrast, each channel in the TPS2000 series is specified at just 37pF capacitance to chassis. As well as providing a safe means of measurement, individual channel isolation allows you to measure multiple signals simultaneously with different ground references, all without ground loop interference! Perhaps best of all, this scheme enables the use of low-cost passive probes, rather than the expensive differential variety. Battery powered Being small and lightweight, these scopes are meant to travel. A lithium- Tek’s TPS2PBND power bundle includes their power measurement and analysis software option. Physically, this consists of a small electronic key and a printed user’s guide. The key is simply inserted into a slot in the front of the scope to enable the software option. Also included in the bundle are four P5120 passive high-voltage probes (only one probe shown here). The CompactFlash card shown is not part of the bundle and can obviously be obtained for a variety of sources. 42  Silicon Chip Two battery compartments are accessible at one end and accept one or two lithium-ion battery packs for up to eight hours running time. siliconchip.com.au Fig.4: turn-off, turn-on and conduction times are easily measured in power switching circuits using the Switching Loss function. Here, channel 1 is being used to measure drain voltage in a MOSFET switching circuit and channel 2 drain current. Other pages allow you to adjust dv/dt and di/dt cursors for maximum measurement flexibility. ion battery pack provides about four hours of continuous use. A second battery compartment (see photo) allows the use of two batteries for double the run time and also means that when one pack runs flat, it can be swapped out without switching the machine off (ie, “hot-swapped”). PC connectivity Getting your measurements onto a PC for analysis and documentation is straightforward. An up-front slot accepts standard CompactFlash cards for storing setups, measurement data and graphics images of the screen. Most popular PC graphics file formats are supported. In addition, a 9-way socket is provided on the rear for connection to a Fig.5: by using the Phase Angle function in the power measurement and analysis software, the relationship between multiple phases can be easily determined. Note that these waveforms were not captured from a 3-phase power generation grid but rather from a demonstration board. PC serial port. In conjunction with the supplied OpenChoice software, data can be saved to disk or acquired directly in Excel for viewing and processing. A Centronics type parallel port is also provided for those that wish to print screens directly. Once again, many popular printer formats are supported. Complete solution For additional cost, Tektronix offer power measurement and analysis software that significantly expands the capabilities of the TPS2000 scopes. This upgrade allows you to make power measurements at the touch of a button in the appropriate units, eliminating the need for manual calculations. Measurements include true power, reactive power, phase angle, crest factor, harmonics and switching loss (including turn-on, turn-off and conduction losses), among others. To seal the deal for power designers and technicians, the power measurement and analysis software (TPS2PWR1) and four new P5120 passive high-voltage probes can be purchased together as a bundle (TPS2PBND). More information For more information on the new range of TPS2000 scopes, contact the Australian distributors, NewTek Instruments on (02) 9888 0100 or point your browser to their web site at www.newtekinstruments.com SC Car Projects, Volume 2 THE PROJECTS: High-Energy Universal Ignition System; High-Energy Multispark CDI System; Programmable Ignition Timing Module; Digital Speed Alarm & Speedometer; Digital Tachometer With LED Display; Digital Voltmeter (12V or 24V); Blocked Filter Alarm; Simple Mixture Display For Fuel-Injected Cars; Motorbike Alarm; Headlight Reminder; Engine Immobiliser Mk.2; Engine Rev Limiter; 4-Channel UHF Remote Control; LED Lighting For Cars; The Booze Buster Breath Tester; Little Dynamite Subwoofer; Neon Tube Modulator. Or order by phoning (02) 9979 5644 & quoting your credit card number; or fax the details to (02) 9979 6503; or mail your order with cheque or credit card details to Silicon Chip Publications, PO Box 139, Collaroy, NSW 2097. siliconchip.com.au Mail order prices: Aust: $14.95 (incl. GST & P&P) NZ/Asia Pacific: $18.00 via airmail Rest of World: $21.50 via airmail January 2005  43