Leakage Current Test Research Articles

Preparation and Ferroelectric Properties of Ho3+/Mo6+ Cosubstituted Bi4Ti3O12 Thin Films by Sol–Gel Method

We have prepared Ho3+/Mo6+ cosubstituted bismuth titanate [(Bi3.6Ho0.4)3.99- Ti2.985Mo0.015O12, BHTM] thin films on Pt/Ti/SiO2/Si substrates using the sol–gel method. The crystal structure and morphology of the BHTM films were characterized. The BHTM samples show a single phase of Bi-layered Aurivillius structure and a dense microstructure. The dielectric constant and dielectric loss of the BHTM films were about 359 and 0.043, respectively, at a frequency of 1 MHz. The films exhibit 2Pr of 57.7 μC/cm2 and 2Ec of 290.0 kV/cm at an applied field of 470 kV/cm, and have fatigue-free characteristics. They also showed good insulating behavior according to leakage current testing.

A Disrespectful Answer

“ Why do customers feel that they can disrespect us?” Biomeds ask this almost daily. I, of course, have an answer. It may even be the answer. But in-house biomeds won't like it. Let me set it up so that I don't hit anyone too hard.Back in the 70s and early 80s, original equipment manufacturers (OEMs)—that is, Mr. Goodwrench—controlled the world. They told hospitals what to buy and how much it would cost. There were few alternatives.Mr. Goodwrench wore a suit, acted professionally, and was respected by the departments he serviced. I provided customer skills training to our service engineers, as we called them, in the early 80s. Anyone who went through the program got a special tie to wear with the required suit. These service engineers had a lot of contact with the people in the radiology department.Biomeds lived in hospital basements, next to the morgue. Occasionally they would pop up to visit nursing floors, grab a box, and disappear. They had little contact with the nurses. Biomeds had no real dress code since they were phantoms who performed leakage current tests on boxes on benches. Many biomed departments still live in the dungeons today and provide essentially the same services.Then something happened. Diagnostic Related Groups (DRG) and other constraints made hospitals more aware of what diagnostic procedures were bundled together and what equipment they could buy. Medicare used DRGs to determine how much to pay, since patients within each category were similar clinically and were expected to use the same level of hospital resources.About that time, I helped start a radiology service training organization, and others started special parts publications. With the availability of training and easier parts acquisition, independent service organizations (ISOs) started to sprout. The founders of these ISOs came mostly from the ranks of the OEM service force. Soon, in-house biomedical departments started training some of their people in radiology service. Now hospitals had three options for service: Mr. Goodwrench, Mr. I M Independent, and Mr. I M Fellow Employee.We had a tough time convincing biomeds that they needed to dress better and act better. Radiology departments had great hesitation allowing the “guys from the basement” to work on their equipment. But 25 years later, we have overcome. Radiology is happy to have qualified individuals work on the equipment, no matter where they are from.In-house biomed has advanced to the level that, in many hospitals, they are the ones to call when something is broken or needs attention. A couple of years ago I had gout in my right hand and went to emergency crying like a 7-year-old. The automatic sliding doors opened partially and slammed shut again. I was powerless to use my hands to open the doors. Someone saw me and pried the doors open, and after wiping the tears from my eyes, yelled out, “Didn't you call someone about this door?” The response: “I called biomed”.In many hospitals, biomeds will do whatever is needed: shoveling snow, repairing flat tires on gurneys, etc. Biomeds are considered jacks-of-all-trades, not highly trained and educated service professionals. Biomeds don't even know what to call themselves.Biomeds need to:There are many biomed departments that are professionally managed and they are thriving wonderfully. These may take great offense to this article. If you are among them, then this was not written about you. I challenge us all to take the medical equipment profession to a much higher level.

Study of Signal Mechanism Based on Combining Magnetic Flux Leakage and Eddy Current Testing

In order to improve sensitivity through information fusion technology, a combined DC magnetic flux leakage and eddy current testing method is proposed. Experimental results indicate that the inner wall cracks in the steel pipe are detected by eddy current system. In fact, the dilemma between the experimental signal and skin effect principle is obviously. Two factors including permeability and magnetic flux leakage that have influence on eddy current signal are analyzed with finite element method and verification experiments of magnetic source. So the viewpoint, that the signal of the internal crack is caused by eddy current effect may be erroneous. Perturbed magnetic field is analyzed by using equivalent source method. Theoretical analysis shows that magnetic flux leakage produced by the crack is far stronger than perturbed magnetic field induced by eddy current effect. The induced electromotive force is created by the variation of the magnetic flux within the cross section of the pick-up coil when the probe moves along the steel pipe with a crack. The signal produced by eddy current effect is submerged. Therefore, the signal of eddy current probe is induced by magnetic flux leakage produced by the crack. Eddy current testing results of ferromagnetic materials under saturation magnetization should be reinterpreted.

Ferroelectric properties of Bi3.4Ho0.6Ti3O12 thin films prepared by sol-gel method

We have prepared the Ho-substituted bismuth titanate (Bi3.4Ho0.6Ti3O12, BHT) thin films on Pt/Ti/SiO2/Si substrates using sol-gel method. The crystal structure and morphology of the films were characterized using X-ray diffraction and atomic force microscopy. The BHT film shows a single phase of Bi-layered Aurivillius structure and dense microstructure. The 2Pr and 2Ec of the 600-nm-thick BHT film were 38.4 μC/cm2 and 376.1 kV/cm, respectively at applied electric field 500 kV/cm. The dielectric constant and dielectric loss are about 310 and 0.015 at a frequency of 1 MHz, respectively. The Pr value decreased to 93% of its pre-fatigue values after 4.46×109 switching cycles at 1 MHz frenquency, and the BHT film shows good insulating behavior according to the test of leakage current.

Preparation and ferroelectric properties of Bi3.4Ce0.6Ti3O12 thin films grown by sol-gel method

We have investigated the preparation and properties of Bi3.4Ce0.6Ti3O12 thin films. The Bi3.4Ce0.6Ti3O12 thin films were fabricated on the Pt/Ti/SiO2/Si substrates using sol-gel method. The structure and morphology of the films were characterized using X-ray diffraction and atomic force microscopy. The thin films showed a perovskite phase and dense microstructure. The dielectric constant and the dissipation factor of the Bi3.4Ce0.6Ti3O12 thin films were about 172 and 0.031 at 1 kHz, respectively. The 2Pr and 2Ec of the Bi3.4Ce0.6Ti3O12 thin films were 67.1 μC/cm2 and 299.7 kV/cm, respectively, under an applied field of 600 kV/cm. The Bi3.4Ce0.6Ti3O12 film did not show fatigue up to 4.46×109 switching cycles at a frequency of 1 MHz, and showed good insulating behavior according to the test of leakage current.

Ferroelectric properties of Bi3.6Ho0.4Ti3O12 thin films prepared by sol-gel method

The Ho-substituted bismuth titanate [(Bi3.6Ho0.4Ti3O12), (BHT)] thin films were prepared on Pt∕Ti∕SiO2∕Si substrates by sol-gel method. The microstructure and electrical properties were investigated. The BHT film consists of a single phase of Bi-layered Aurivillius structure. The surface is uniform, smooth, crack-free, and with a dense microstructure. The 600-nm-thick film exhibits 2Pr of 44.2μC∕cm2 and 2Ec of 323.7kV∕cm at 500kV∕cm. After the switching of 4.46×109cycles, the BHT film shows fatigue-free (only 3% degradation). The dielectric constant and dielectric loss are about 489 and 0.018 at a frequency of 1MHz, respectively. The BHT film shows good insulating behavior according to the test of leakage current.

Ferroelectric properties of Bi4Zr0.5Ti2.5O12 thin films prepared on LaNiO3 bottom electrode by sol-gel method

The Bi4Zr0.5Ti2.5O12 (BZT) thin films were fabricated on the LaNiO3 bottom electrode using sol-gel method. The structure and morphology of the films were characterized using X-ray diffraction, AFM and SEM. The results show that the films have a perovskite phase and dense microstructure. The 2P r and 2V c of the Pt/BZT/LaNiO3 capacitor are 28.2 μC/cm2 and 14.7 V respectively at an applied voltage of 25 V. After the switching of 1×1010 cycles, the P r value decreases to 87% of its pre-fatigue values. The dielectric constant (ɛ) and the dissipation factor (tanδ) of the BZT thin films are about 204 and 0.029 at 1 kHz, respectively. The films show good insulating behavior according to the test of leakage current. The clockwise C-V hysteresis curve observed shows that the Pt/BZT/LaNiO3 structure has a memory effect because of the BZT film’s ferroelectric polarization.

Suitability of electrosurgical analysers for routine maintenance testing of electrosurgery units – a technical note

Primary objective: To evaluate the use of electrosurgical analysers in testing power output and leakage current from an electrosurgery unit and compare this to the manufacturer recommendations for routine testing.Method: Two electrosurgical analysers were compared to reference measurements (carried out using non-inductive resistors, a current transformer and oscilloscope) over a range of tests described in IEC 60601-2-2: 1998 measuring power output and leakage currents in different conditions. The analysers used were Metron QA-ES and Fluke 454A.Outcomes: Both analysers gave similar results to the reference measurements for power output. The Metron QA-ES gave similar results to the reference measurements for leakage current testing; however the Fluke 454A gave substantially different results when used as described in the manual.Conclusions: Electrosurgical analysers can be a valuable tool in the workshop, enabling rapid, accurate testing of electrosurgery equipment without needing additional equipment and setting up times. Not all analysers can perform all the tests that may be needed and in some cases the accuracy of the results is questionable. Users must be certain of the capabilities and limitations of the analyser before making decisions based on the results.

Preparation and ferroelectric properties of Bi4Zr0.5Ti2.5O12 thin films on LaNiO3 bottom electrode by the sol–gel method

We have investigated the preparation and properties of Bi4Zr0.5Ti2.5O12 thin films on the LaNiO3 bottom electrode. The Bi4Zr0.5Ti2.5O12 thin films were fabricated on the LaNiO3 bottom electrode using the sol–gel method. The structure and morphology of the films were characterized using x-ray diffraction and scanning electron microscopy. The results show that the films are a perovskite phase with a dense microstructure. The 2Pr and 2Vc of the Pt/BZT/LaNiO3 capacitor are 28.2 µC cm−2 and 14.7 V respectively under the applied voltage of 25 V. After the switching of 1 × 1010 cycles, the Pr value decreases to 87% of its pre-fatigue values. The dielectric constant and the dielectric loss are about 204 and 0.024 at 1 kHz, respectively. The films show good insulating behaviour according to the test of leakage current.

Condition assessment of distribution PILC cables from electrical, chemical, and dielectric measurements

A study was conducted to evaluate some new diagnostic techniques enabling users to effectively manage their paper-insulated, lead-covered (PILC) cable assets. The objective is to present the results obtained with four diagnostic techniques designed for use on in-service cables, but used only to a limited extent on PILC cables. These techniques are LIpATEST leakage current test method, isothermal relaxation current (IRC), return voltage method (RVM), and dielectric spectroscopy. In addition, the AC breakdown strength of the cable was also measured. The differences between the titration measurements and the predictions made by AC breakdown and the non-destructive techniques, such as RVM and dielectric spectroscopy, were noted with specific reference to moisture content in the cables. The different diagnostic techniques used in the study gave a reasonably consistent and coherent evaluation of the insulation condition of several field-aged PILC cables. The moisture content deduced from RVM and dielectric spectroscopy does not agree with Karl-Fischer titration of the same samples. It is suggested that aging induces more detrimental polarization processes in the cable oil, whose impact on electrical properties is still unknown but appears to be much more influential than moisture for the cables tested. The results confirm a previous suggestion that PILC cables kept under load are not significantly affected by water ingress.

Thermal stress effects on capacitance and current characteristics of Cu/Si and Cu/TiN/Si Schottky-diodes

Schottky diodes are discussed as an alternative for pn junctions for application to Cu diffusion barrier tests. The Cu/TiN/p-Si system seems very promising for sensitive leakage current tests since Cu is shown to have a significantly lower barrier height to p-Si (0.55 + 0.01 eV as deposited) than TiN (0.90±0.01 eV after 300°C, 60 min). Furthermore the TiN/p-Si diodes maintain a high Schottky barrier even after annealing at 700°C (0.8±0.01 eV). An application of the proposed barrier test is given by an investigation of the thickness and N 2 flow dependence of reactively sputtered TiN diffusion barrier stability. While most samples show increased leakage currents after 450°C, the one with the 20 nm TiN barrier maintains its low leakage current up to 500°C annealing.

Breakdown mechanisms in PZT thin film capacitors

Abstract Breakdowns of PZT thin film capacitors were demonstrated by applying input signals such as DC bias, square waves, triangular waves, and unipolar pulse. Effects of frequency, capacitor size, and pulse width on breakdown were investigated in order to understand breakdown mechanisms. It was confirmed that impulse breakdown is related to rise time of the input signal in association with charging time of the capacitors and steady-state thermal breakdown, pulse width. Energy stored in the ferroelectric capacitors during hysteretic cycling may be additional thermal breakdown source. Electrode burst was observed which may occur due to thermal breakdown through grain boundaries. In addition to breakdown, a new leakage current test technique for FRAM application was suggested in consideration of transient current of the capacitors. In conclusion, breakdown is more serious and leakage current is less serious in FRAM applications than in DRAM applications. Finally, homogeneous polycrystalline structure or si...

Field and test experience with insulating rope at BPA

Test standards for evaluation rope used for hotline work or work in the proximity of energized power lines need to be revised. Field and test experience with polydacron rope demonstrates that rope test standards need to include a leakage current measurement method that minimizes capacitive current; to increase the time requirement for the 60 Hz 100 kV/ft dry withstand test; to revise the method of performing wet leakage current tests; and to increase the voltage stress level for wet tests.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Tantalum Oxide-Silicon Oxide Duplex Dielectric Thin-Film Capacitors

Tantalum oxide possesses several outstanding characteristics as a dielectric for thin-film capacitors: a relatively high dielectric strength, a high capacitance-to-area ratio, and good mechanical and electrical stability. The high capacitance density, however, becomes a disadvantage for capacitors in the range of about 100 pF and below. Silicon oxide has been widely investigated as a dielectric for low value capacitors, but it is limited by pinhole defects. By depositing SiO on Ta <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</inf> to form a duplex dielectric structure, low value capacitors and large area distributed RC networks can be realized and incorporated into tantalum integrated circuitry. Because of the small probability of alignment between defects in the two dielectrics, high initial yields and improved long-term reliability have been obtained. Duplex dielectric capacitors were prepared on glass substrates by anodization of sputtered beta tantalum electrodes and vacuum sublimation of bulk silicon monoxide. Variables studied were silicon oxide thickness and gold versus nichrome-gold counterelectrodes. Comparative evaluations were made by leakage current tests and life tests at several voltages and temperatures. A 75-volt dc leakage current criterion indicates that high initial capacitor yields of 98-100 percent can be obtained with 130-volt anodic Ta <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</inf> , either 2800 .Å or 5000 Å of silicon oxide, and both types of counterelectrode. These capacitors perform reliably at 50 volts and 85°C. Capacitors with gold counterelectrodes and the thicker films of silicon oxide exhibited a lower failure rate at the higher life test voltages and temperatures

In-Circuit Transistor Leakage Current Testing

An instrument capable of measuring leakage current of transistors while the trarisistor remains in the circuit was developed. This instrument gives an accurate leakage current measurement in a large variety of circuits as well as being simple to operate, lightweight, battery powered, and portable for use in the field. This was accomplished by the measurement of the transistor leakage current ICBX, which is the collector current when both the collector and emitter junctions of the transistor are reverse biased. This particular leakage current was chosen because it is nearly independent of the gain parameters of the transistor and a very close approximation to the fundamental leakage current ICBO. The present instrument measures leakage currents as low as 1 µa with a collector load resistance down to 500 Ω. At present, an accurate instrument is not commercially available for measuring transistor leakage current in the circuit. The results presented in this paper indicate a method for adding the capability of measuring in-circuit transistor leakage current to future transistor testers.

High-Voltage Measurements on Cables and Insulators

This paper presents some of the results of a series of high-voltage tests on cables and insulators, extending over a period of eight years, to determine the electrical characteristics of the insulation. Leakage current, insulation resistance, and watt input tests were made with direct and alternating current. Paper-insulated and rubber-insulated cables and a 27,000-volt porcelain insulator were tested. From these tests several conclusions were drawn, the principal ones being as follows: 1. Insulation resistance of paper and rubber-insulated power cables increases to a maximum with increasing applied d-c. voltage, the characteristic depending upon the temperature. 2. It is necessary to use shields as well as guards in making tests to determine the electrical characteristics of cable insulation under d-c. voltage stresses above the ionization point. 3. The watt input to the insulation of a paper cable under d-c. stress, at a given temperature, depends upon the character of the voltage wave; the greater the ripple, the greater the watt input. 4. It is necessary to use shields as well as guards in making tests on short cable samples to determine the a-c. electrical characteristics, such as dielectric loss of cable insulation under voltage stresses above the ionization point. 5. The ionization point is very variable depending upon the physical circuit, together with the atmospheric conditions, and represents, in reality, local air breakdown. 6. The better (i. e.