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
EEVblog #605 – Fig.8 & Cardioid Microphone Patterns
Doug Ford, former head designer from Rode Microphones continues with...
eevblog.com
Hubble Turns 24: 5 Biggest Discoveries
The Hubble Space Telescope has helped solve huge questions about...
eetimes.com
Samsung Defense: Marketing Guru vs. Marketing Guru
Parade of marketing and programming experts continues as Samsung tries...
eetimes.com
IoT: A Return to Our Favorite EDA Requirements
For the electronic design automation (EDA) industry, the Internet of...
eetimes.com
Life Without DropBox? Unthinkable!
Once you've installed the DropBox app on your computers, anytime...
eetimes.com
New IC for Driverless LEDs
A Eurolighting module produces flicker-free LED light from 230 VAC....
eetimes.com
SanDisk Finds Profit Behind the Tech Curve
Focus and frugality put SanDisk in several sweet spots in...
eetimes.com
Will 'Makers' Help Chip Guys' Bottom Line?
Are you seeing this newborn love among "makers," board vendors,...
eetimes.com
Where Are DRAM Interfaces Headed?
What comes after today's fastest interfaces? Jim Handy talks about...
eetimes.com
IoT Requires Continuous Development
The Internet of Things will add so much programmability to...
eetimes.com
AMD Narrows Its Losses in Q1
As sales of PC continue to decline, AMD is looking...
eetimes.com
Quantum-Dot Windows Harvest Solar Energy
The windows of the future could harvest the sunlight passing...
eetimes.com
Patent Lessons From Apple v. Samsung
The Apple v. Samsung case exposes vast gray areas in...
eetimes.com
Fitness Wearables Lack Accuracy
A new generation of wearable fitness sensors is needed to...
eetimes.com
Bagels: Official Food of Test & Measurement
A bagel is the perfect food to eat at your...
eetimes.com
Max's BADASS Display, Part 3
Now we come to consider the various ways in which...
eetimes.com
Smartphones, 28nm Tech Drive TSMC 1Q Revenue
Thanks to demand for high-end smartphones and investment in technology...
eetimes.com
Quantenna Speeds Up WiFi
As several major companies roll out 802.11ac solutions with multi-user,...
eetimes.com
Samsung Patent Leaks Point to Google Glass Competitor
In a series of leaked patent documents from South Korea,...
eetimes.com
IMEC Adds Image Sensors to Commercial Development Service
The Belgian company has published a brochure that boasts of...
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 +