Testing Capacitor - How To Test A Capacitor When Breakdown Under Load

Testing Capacitor - How To Test A Capacitor When Breakdown Under Load-How To Study For A Test

Have you ever come over power question where once you switch on the power furnish and the fuse blow? You have checked all the components in the power (primary) and secondary section and all the components seems to be ok! Where is the fault? A fuse blown are usually caused by a shorted bridge rectifier, defective posistor, power transistor or Fet, shorted original winding of switch mode power transformer, shorted secondary diode and etc. But in this article I'm gone to show you another inexpressive of electronic troubleshooting tips.

How To Study For A Test

I got frustrated as to where is the cause of power problem. Every time when i switch on the power furnish the fuse blow immediately (the fuse became dark color and this indicate that there is a major short circuit in the power supply). I have checked all the components in the power furnish and can't find the culprit! What i do is i desoldered all the suspected parts one by one and supplanted with a known good component. I eventually found the caused of the power furnish problem. Guess what? It was the main filter capacitor (220 microfarad 400 volt). After replacing the filter cap the power furnish worked perfectly fine. I begin my detective work to find out why this capacitor can caused the fuse to blow even though i already confirmed it ok with my meters.

The meters that i used to check the filter cap were analog meter, digital capacitance meter and esr meter. In this article i will not justify about how to check capacitor or testing capacitor and how capacitor work. I believed most of you know how to check capacitors and also ordinarily using this type of meters. Measured with analog it showed capacitor charging and discharge, with digital capacitor tester it showed around 220 microfarad and with esr meter it showed low esr reading!

This proved that the bad capacitor breakdown when under full operating voltage. Then, how do i confirm that this filter capacitor is faulty? By using an analog insulation tester. When i join together the faulty cap to the meter and press the go button-it showed a very low resistance and this is the proved of short circuit in the middle of the plate when voltage applied! There is nothing to do with bad electrolyte. A good capacitor will just showed a payment and dismissal in the insulation meter just like you are checking a capacitor using analog multimeter. In the shop there is quite a estimate of ranges that you can buy. It has the range of 50v, 100v, 250v, 500v, 1000v and even 5000v! If you want to test a capacitor of 100 microfarad 160v then you have to pick 100v. If you pick 250v, it will blow your capacitor that is under test.

If you have the Sencore Test equipment such as the sencore lc meter Lc102 Or Lc103, these meters have the capabilities of checking any type of capacitors with four tests:

-testing for capacitor values

-checking for leakage

-equivalent series resistance (Esr) and

-Dielectric absorption

It can check aluminum electrolytic capacitor, film capacitor, ceramic, high voltage capacitor and etc.

Conclusion-Different capacitor constructor produced different type of capability of a capacitor. Perhaps the bad capacitor that I encountered are from the lowest grade one. A capacitor failure when under load is very rare. Using Esr capacitor meter alone can solve most of the electrolytic capacitor problem.

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Psychological Testing - Advantages and Disadvantages

Psychological tests are used for evaluation and evaluation of the test taker by a competent examiner. That is why it is also called psychological assessment. But of course, the tests can only be accurate and trustworthy if you acknowledge it carefully, authentically and seriously.

A competent psychologist is ordinarily the examiner of these psychological tests. But it should be noted that psychological tests are advantageous only in confident situations. Free psychological tests circulated through the internet are regularly bests for entertainment purposes.

So what are some beneficial types of psychological tests? Tests that part your knowledge about a confident exact topic, or capacity for confident skills are called achievement and aptitude tests. Intelligence tests would say about your general quality to know the world colse to you. It also assesses how you use the Intelligence to adapt to the world, and in what manner you apply this general ability. Therefore, we can say that the focus of Intelligence tests is potential. Neuropsychological tests part loss in functions of cognitive ability. Occupational tests are used to match your interests with the interests spicy a confident occupation or occupation. Personality tests try to conclude the style of your personality regularly for clinical or forensic purposes. exact clinical tests refer to tests that part confident exact levels within a person in terms of his or her state of mind, like depression or anxiety.

One great advantage for using or taking psychological tests is that it is quite difficult to lie. For example, the Rorschach test does not offer any clue for the test taker about what would be a healthy response or an unhealthy response to the questions asked by the test. In this way, biases for production a favorable or an unfavorable impression can be avoided. Someone else advantage is the scientific consistency present through the test that cannot be found in clinical interviews. For instance, when it comes to legal situations, these tests can be more helpful than interviews. And last but not the least; data can be more authentically taken from tests instead of interviews. Both psychologists and clients can compromise the reliability of clinical interviews.

However, sometimes tests do not authentically part what they are supposed to measure. Therefore always remember the following guidelines:
• Always identify the purpose of testing.
• Identify the names and rationales of the tests.
• Always get the results of the tests.

Remember these guidelines, and always refer to a psychologist you trust.

Testing a Transformer - How To Accurately Test A Transformer

There is two types of transformers in the market- linear transformer and switch mode power transformer. The transformers produce is different. Sometimes it is just referred as ac transformer. Linear transformer mostly used in radio, scheme kits, Vcd and etc while switch mode transformer can be found in Monitor, Tv, Fax and so on.

A transformer consists of two or more coils wound on the same core. For power transformers, the core material is usually iron. For a radio-frequency transformer, the core material is usually ferrite or air. The basic asset of a transformer is to turn Ac voltage. A transformer cannot turn direct current voltage. A step down transformer has a lower Ac yield voltage at its secondary winding than the Ac input voltage to its primary winding. Conversely, a step up transformer has a higher secondary than primary voltage. The transformer laminations or coating of shellac, enamel or varnish is to insulate adjacent turns from shorts between winding. I will not go too details about how transformer work and transformer calculation as you can read more details from most electrical and electronic transformers books.

How to test transformers: Transformer failures are relatively rare in most electronic equipment, compared with other components. If too much current goes through a coil or winding, the winding heats up and can whether open up completely, or the insulation between turns of wire can break down, causing the coil to be partly or thoroughly shorted.

Just like a coil, you can check continuity of any primary or secondary transformer winding. The actual value of Dc resistance you read is rather meaningless, but at least you will know whether a winding is open. Checking linear transformer is quite straight forward. Apply the ac voltage to the primary winding and expect yield voltage at the secondary side. No or low yield voltage means the transformer winding has open or shorted winding. Look for any evidence of overheating, such as darkened or blackened areas or a burnt smell.

About how to test a power transformer-it is a little bit complicated. You cannot apply ac voltage to the equipment and expect the desire yield at the secondary side without associate to load otherwise over voltage will happen (because you have removed all the secondary load) and will blow the power section which consist of power fet, pwm ic and etc. Switch mode power supply are designed to run with load while linear transformer can be test without load.

The best way to test a switch mode power transformer is first take off it from the board. Check only the primary winding as secondary winding failures are exceedingly rare. How do we know which one is the primary winding? Trace from the big filter cap the inescapable pin to see where the circuit goes. It will go to one of the pin of the transformer. Then look for the power fet middle pin which is the Drain and it will lead to another pin of the transformer. This two pins is the primary winding of the transformer. Checking the resistance of the primary winding only can delineate whether it is open but it cannot check if it has advanced a shorted winding. Only by using a ringer test you will know if it shorted or not. A shorted turn in the primary winding can cause the power section to blow.

The cheapest ringer tester that i came over is Dick Smith Lopt Meter or flyback tester. Just associate the probes to the primary winding and the consequent are right away seen from the Led bar graph. 4-8 bar record a good winding, 1-2 bar record partial short and if the led goes off means there is a heavy short in the winding. Also checking the transformer it can be use to check B+ Coil, horizontal yoke coil and flyback primary winding and ballast (choke).

The high-priced ringer tester is from sencore equipment. Sencore Lc102 and Lc103C Also checking capacitor it also have the quality to check all kind of winding. whether it is a low voltage transformer, high voltage transformer, current transformer, pulse transformer, electric transformer, convention transformer this equipment will be able to check and test it.

If you do not wish to spend on this tester you may use a light bulb to check it. take off one of the primary winding pin and associate a 60 watt light bulb. One end to the circuit while the other to the transformer pin. If the bulb light and didn't goes off imagine a shorted winding and if the light goes off, the winding is ok.

Transformer mend is not easy and it require a good skill to do it. Most of the transformer repairer preferred to rewind bigger winding such as fan, car alternator and starter. Switch mode power transformer is a little bit difficult to rewind because of the small size and low price.