Quantcast CAPACITOR MEASUREMENTS

Share on Google+Share on FacebookShare on LinkedInShare on TwitterShare on DiggShare on Stumble Upon
Custom Search
 
  
 
1-15 DIFFERENTIAL VOLTMETERS It is a seldom-known fact that the Fluke 893 ac-dc differential voltmeter can be used for measuring extremely high resistances from 10 megohms to 106 megohms with a typical accuracy of 5%. This measurement method, however, requires some basic calculations on your part. The obvious advantage of the differential voltmeter is its capability of measuring extremely high resistances. Consult the Fluke 893 technical manual for initial switch settings and a more detailed explanation of its operation. CAPACITOR MEASUREMENTS Capacitance is that property of a circuit that produces an electrostatic field when two conducting bodies separated by a dielectric material have a potential applied to them. Capacitors are made by compressing an insulating material (dielectric) between two conductors (plates). The farad is the basic measurement of capacitance. It is dependent upon the area of the plates, the distance between the plates, and the type of dielectric used. Electrically, the farad is a measure of 1 coulomb of potential charged by 1 volt. A coulomb (the amount of current flow maintained at 1 ampere that passes a given point of a circuit in 1 second) is a large charge. Most capacitors are measured in millionths of a farad (microfarad), expressed as F, or in one-millionth of a microfarad (picofarad), expressed as pF. Capacitors incur various losses as a result of such factors as resistance in the conductors (plates) or leads, current leakage, and dielectric absorption, all of which affect the power factor of the capacitor. Theoretically, the power factor of an ideal capacitor should be zero; however, the losses listed above cause the power factors of practical capacitors to range from near 0 to a possible 100%. The average power factor for good capacitors, excluding electrolytics, is 2% to 3%. Current leakage, which is an inverse function of frequency, is important only at the lower frequencies and becomes negligible at higher frequencies. Dielectric absorption (sometimes referred to as dielectric viscosity) results in losses that produce heat. The effect of this type of loss is the same as resistance in series with the capacitor. You have probably learned the hard way that some capacitors can retain a charge long after the voltage has been removed. The electrical charge retained by capacitors in de-energized electronic circuits is, in many cases, sufficient to cause a lethal shock. Be sure you and those working with you consider this hazard before performing any type of maintenance on any electrical or electronic circuit and before making connections to a seemingly dead circuit. Use extreme caution prior to working on or near de- energized circuits that employ large capacitors. Be safe—discharge and ground all high-voltage capacitors and exposed high-voltage terminal leads by using only an authorized shorting probe, as shown in figure 1-11. Repeat discharge operations several times to make sure that all high-voltage terminations are completely discharged. It is of the utmost importance that you use only an authorized safety shorting probe to discharge the circuits before performing any work on them. An authorized general-purpose safety shorting probe for naval service application may be requisitioned using the current stock number listed in the ELECTRONICS INSTALLATION AND MAINTENANCE BOOK (EIBM), General NAVSEA 0967-LP-000-0100, Section 3, Safety Equipment. Certain electronic equipment are provided with built-in, special-purpose safety shorting probes. These probes are not considered general purpose. Use them only with the equipment for which they are provided and only in a manner specified by the technical manuals for the equipment. It is considered to be poor practice to remove them for use elsewhere.


Electrical News
Talking Sheets, Thinking Shorts
The tagging of garments via RFID-based labels has been commonplace...
eetimes.com
Ericsson Layoffs Target R&D, Supply
Ericsson will release 10% of its Swedish workforce as part...
eetimes.com
Sneak Peak! RTOS Smackdown at ESC Silicon Valley 2015
At ESC Silicon Valley, seven of the leanest, meanest, coolest,...
eetimes.com
Merck Buys Display Quantum Dot Company
Merck KGaA (Darmstadt, Germany) has announced it is acquiring Qlight...
eetimes.com
Bringing More Affinity and Testability to Multicore
To make its affinity-based RTOS scheduling algorithm for multicore software...
eetimes.com
Micron Remains Optimistic Despite Down Quarter
Sluggish PC market affected DRAM growth, but company appears confident...
eetimes.com
Selecting Your M&A Banker
At some point in the life of a technology startup...
eetimes.com
DoT Call for Proposals, Registration Open
The IoT, wearables, and 3D printing-focused Designers of Things conference...
eetimes.com
Automotive King Redefines Future
By 2030 the cost of an automobile will be mostly...
eetimes.com
8 FD-SOI Questions You're Afraid to Ask
Paul Boudre, CEO of Soitec, told us last week in...
eetimes.com
New Architectures Target 5G Power Needs
The next generation of mobile telephony is not so far...
eetimes.com
Synopsys Acquires Elliptic Technologies, Beefs up Security
Synopsys, Inc. is acquiring security intellectual property company Elliptic Technologies....
eetimes.com
EEVblog #759 – Mailbag
A big mailbag episode, getting through lots of backlog. P.S....
eevblog.com
Back in the Driver's Seat on Global Trade
The Trade Promotion Authority (TPA) is a major victory for...
eetimes.com
Back in the Driver's Seat on Global Trade
The Trade Promotion Authority (TPA) is a major victory for...
eetimes.com
Slideshow: IMEC Innovates in Wireless
Here are some wireless innovations from IMEC, one of Europe's...
eetimes.com
Gobsmacking Graphic Novels
Max recently became enthralled with a bunch of new graphic...
eetimes.com
Smartphone Saturation Becomes OEM Conundrum
Smartphone sales are down and OEMs should be worried. Creating...
eetimes.com
Rounding Algorithms Can Be Tricky
There's a lot more to the topic of rounding than...
eetimes.com
DAC Trip Report: Expanding EDA's Charter & Topical Hardware Emulation
Dr. Lauro Rizzatti paid close attention to trends at DAC...
eetimes.com
 


Privacy Statement - Copyright Information. - Contact Us

comments powered by Disqus

Integrated Publishing, Inc.
9438 US Hwy 19N #311 Port Richey, FL 34668

Phone For Parts Inquiries: (727) 755-3260
Google +