DTS-1600A dielectric test system the use of pulse width modulated (pwm) types of adjustable speed drives (asd) in the electric motor in- dustry has caused an increased inci- dence of premature wire insulation fail- ure. the DTS-1600A is an integrated test system designed to test the failure behavior of insulation by simulating, under controlled and accelerated con- ditions, the electrical and thermal stresses that characterize pwm (inverter) motor controllers. the DTS-1600A test system is de- signed to vary and monitor the electri- cal and thermal test parameters for up to five samples simultaneously, includ- ing voltage, current, pulse width, fre- quency, voltage rate-of-rise time, duty cycle and temperature. the control and monitoring of these parameters allows the user to study the insulation failure mechanisms common to pwm applications. this data can then be used in the development of new motor designs and insulation that will over- come these failure modes. compared to testing with an inverter, the DTS-1600A can reduce the test time from days per sample to minutes per sample (time-to-failure with the DTS-1600A is typically 1,000 times faster than with an inverter), dramati- cally reducing research and develop- ment time for new insulating materials. equally important, full control over the electrical and thermal test parameters provides a reproducible test environ- the pulse of the future directed energy, inc. ? 2401 research blvd., suite 108 ? fort collins, co 80526 tel: 970-493-1901 ? fax: 970-493-1903 ? email: deiinfo@directedenergy.com ? internet: http://www.directedenergy.com ? 5-channel 3,200v pulsed test system for accelerated breakdown testing of motorettes, twisted-pair and dielectric materials ? variable output voltage, pulse rate- of-rise time, frequency, duty cycle and temperature ? graphical user interface and computer control and logging of test and oven parameters DTS-1600A dielectric test system
operational overview the DTS-1600A is designed to meet the testing requirements of magnet wire manufacturers, mo- tor designers and manufacturers, and manufac- turers of varnish and insulating materials. the DTS-1600A will test up to five samples (twisted pairs, motorettes or dielectric material) simultaneously. the samples are installed in the oven to facilitate testing at controlled and ele- vated temperatures. the test parameters are con- trolled and monitored through the control com- puter. each channel can be individually enabled or disabled, and programmed for current trip threshold and voltage rise and fall time. the pulse frequency, pulse width, amplitude (voltage) and oven temperature are shared by all five channels. the system can simultaneously pulse five capaci- tive samples of 50pf (a typical twisted pair) per sample or three samples of 350pf each (a typical motorette) at 20khz frequency at 1600v (3200v peak-to-peak) in bipolar mode. (higher capaci- tance loads can be driven at derated voltage and/ or frequency.) it can also drive an inductive load, such as a motor stator, of 3mh at up to 3.5 s pulse width and 1600v (typical operating parame- ters) in unipolar mode. typical output wave forms are shown in figures 1, 2 and 3. when a sample under test fails (the charging cur- rent exceeds the current threshold, indicating the sample has shorted or arced), the channel is dis- abled, and the failure information is logged to a text file and displayed on the graphical user in- terface (gui) monitor. in addition to the parame- ters displayed and controlled through the gui dis- play, each channel has current and voltage moni- tor outputs that can be monitored using an oscil- loscope or digitizer for real-time data acquisition of the voltage and current profiles for each sam- ple during operation. the DTS-1600A is controlled by its control com- puter and gui, which provides the interface be- ment in which time-to-failure is repeatable within statistically allowable differences. for all practical purposes, inverters do not offer this capability. in addition, the DTS-1600A offers other advan- tages over testing using an inverter. these ad- vantages include: ? capable of testing up to 5 samples simultane- ously. ? user-controlled, variable voltage, current trip- point, pulse width, frequency, duty cycle, volt- age rise and fall time and sample tempera- ture. ? computer control and logging of the test pa- rameters and failure data. the DTS-1600A was developed in collaboration with the u.s. electrical motors division of emer- son electric, utilizing a patented test technique developed by usem (1) . (1) licensed under us patent #5,648,725 and copyright of the em- erson electric company, 1996 figure 1 typical rise time (~31ns) on fastest rise time setting, driving a twisted pair (~50pf), 1600v figure 2 typical current (top trace) and voltage (bottom trace) wave- forms, driving a twisted pair (~50pf), 1600v figure 3 typical voltage waveform (top trace) at 20khz repetition rate (bottom trace), driving a twisted pair (~50pf), 1600v
system overview the DTS-1600A system consists of three basic modules. the first module is the pentium proces- sor-based control computer and general purpose interface bus (gpib). the computer and gui op- erate as the master control unit, and allow the user to interface with the system. using software created in the national instruments labwindows/ cvi environment with custom defined functions, the user has complete control of the system from this location. the control computer interfaces to the slave control unit over a gpib bus. the rack-mounted slave control unit and high voltage section is the second module. it consists of a gpib interface, a microcontroller and pulse generator, five 1600v pulser modules, oven control circuitry, front panel interface, and high voltage and support power supplies. the internal microcontroller is responsible for decoding the software commands from the control computer and implementing them in hardware. it communi- cates with all peripheral cards via an internal rs- 485 interface. tween the system and the user. designed with the research and manufacturing environments in mind, the gui allows the user to configure and monitor all samples under test. created with na- tional instruments labwindows under windows 95, the control screens appear like the front panel of a test instrument. using a mouse and key- board, the software is intuitive and easy to learn, requiring very little time and energy to become proficient in the control of the DTS-1600A. the gui provides control over the following pa- rameters: ? output voltage from 0 to 1600v ? pulse width from 1 s to 4.75ms ? pulse frequency from 200hz to 20khz ? oven temperature from ambient to 180 c ? enable/disable testing of each sample ? pulse rate-of-rise time for each sample ? current trip setpoint for each sample ? file logging of all test data test data are logged in a standard ascii text file. from this file, the user can retrieve data corre- sponding to the start of each sample test, failures of individual samples, as well as periodic test pa- rameter updates. the log file can be imported into and analyzed using a spreadsheet program such as microsoft excel or lotus 1-2-3. figure 4 gui main control panel the main gui control screen is shown in figure 4 above. the DTS-1600A is a fully integrated test system, ready for use. the control software is designed to enable immediate use of the system, without ad- ditional programming on the part of the user.
the pulse of the future directed energy, inc. ? 2401 research blvd., suite 108 ? fort collins, co 80526 tel: 970-493-1901 ? fax: 970-493-1903 ? email: deiinfo@directedenergy.com ? internet: http://www.directedenergy.com 9200-0203 rev 2 dei supplies solutions for the generation, delivery and measurement of high power, high fidelity electrical pulses. applications include lasers, test and measurement, mass spectroscopy, radar and acoustics. please call, fax or email for applications assistance or information on other dei products. the third and final module is the oven and test fixturing. this is where the actual samples under test are placed. the oven is a blue m model mo1420a (or equivalent), forced air convection oven, proportionally regulated to a maximum of 180 c. the forced air convection oven provides adequate air flow to dissipate ozone build up in the oven created by corona during testing. the system is housed in a standard 19" equip- ment rack, 31" deep and 36" high. included in the rack are the slave controller and pulse generator, five high voltage pulser modules and control cir- cuitry, high voltage dc and support power sup- plies, a universal input voltage transformer, and a rack circuit breaker. the benchtop oven sits on top of the rack, and interconnects with the pulser and control circuitry with an umbilical cable. the control computer and monitor are a standard pentium-based desktop pc, that connect to the rack with a 2 meter gpib cable (included with the system). this allows the test station to be a com- plete stand-alone instrument. for operator safety, the oven door is interlocked. the system features front panel status indicators, and an emergency stop button to allow immediate shutdown of the system, if necessary. ordering information the DTS-1600A is delivered as a fully integrated, turnkey system complete with control computer and software, oven, slave controller/high voltage sections and equipment rack, ready for immedi- ate use. test fixtures for twisted pair, motorettes and dielectric samples are available through dei. for further information and for price and delivery, contact the factory, or the dei representative in your area. references and related papers ?aging of magnet wire in the presence of variable fre- quency, high rise time and high voltage pulses?, v. divljakovic, j. kline, d. barta, d. floryan, ceidp 1994. ?pulse width modulated aging twisted pairs, motorettes. and motors?, j. kline, v. divljakovic, g. krausse, emcw 1996. ?available insulation systems for pwm inverter-fed motors?, a. bonnett, ieee industry applications magazine, january/ february 1998 specifications pulse specifications pulse amplitude variable from 0 to 3,200v peak-to- peak (1600v) pulse frequency variable from 200hz to 20khz pulse width variable from 1 s to 4.75ms duty cycle variable from 0.002% to 95% pulse rise and fall times variable from 50ns to 200ns (1) load capacitive (twisted pairs or motor- ettes): max 5 twisted pair (50pf each) or 3 motorettes (350pf each) at 20khz frequency, 1600v (2) inductive (stator): 3mh at 3.5 s pulse width, 1600v unipolar, 20khz oven specifications min. temperature ambient max. temperature 180 celsius monitor signal specifications voltage monitor 1000 volts/volt into 50 ohms current monitor 10 amps/volt into 1 meg-ohm sync ttl into 50 ohm control computer specifications general specifica- tions 733 mhz pentium, 64mb ram, 10gb hdd, cd rom, 3?? fdd, 15? monitor, mouse & keyboard (3) ac input 100/120vac @ 20a, 50/60hz 208/220/240vac @ 10a, 50/60hz power specifications s pecifications subject to change without notice . notes: (1) specified into a 50pf load (typical twisted pair) installed in an oven fixture. actual rise and fall times will vary somewhat based upon load capacitance. the rise and fall time are user selectable in 8 steps. (2) maximum load capacitance is limited by the power dissipa- tion of the system. higher load capacitances can be driven at derated voltages and/or frequency. (3) minimum specifications. computer may have better specifi- cations, depending upon configurations available at time of order.
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