Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.
I think that the problem is related to my DMM.
My DMM is suitable to measure direct voltage up to 1000VDC,
but apparently,it is not suitable more this task.
Thanks for your response.:)
I don't know what happens without the MOV,since the purpose of the
circuit is to test the MOV.
The value of the resistor is changing,depend on how much i want to drop the
voltage on the resistor in order to get the correct voltage on the MOV,but let
say 110K ohm.
The wiring and the resistor...
Hi.
The above circuit contains:megger,mov,resistor and DC
voltmeter and it for checking the clamping voltage of the varistor at 1mA.
My question is not about the purpose of this circuit or if it give an accurate
results,but to the phenomenons that i got,while pressing the 500VDC on the megger...
I read again the thread and i would like to clarify something.
You said that the epoxy case gets about 1/3rd as hot as the semiconductor inside.
So if in the datasheet it says that the max junction temperature is 150°C,
Does it mean that the epoxy case temperature must not exceed 50°C(1/3 of...
If i understand right,i can assume that the 10 seconds warning is probably refer also to short circuit(0-Rmin).And i can verify that by checking the thermal resistance of the transistor by IR thermometer.
I guess that i can only measured the temperature of the case
and not the die inside.So the...
And what parameters should i look for?how much T rise?
Is it the maximum temperature(100°C-150°C)of of the TO-220 transistor?
What temperature of the transistor,after 5 sec,should tell
me that the circuit is approaching its limits?
Unfortunately,i couldn't make a contact with the
company who made this megger.
The megger is a non expensive made in china tool
and in the manual there is no(as you mentioned)
qualifier for the R value in the 10 sec limit.
Anyway,thanks for your help.
if i will smell something burning inside the...
I forgot to add an important spec.
On short circuit the current limiting circuit is limit the current to
about 2.5mA.
Yes,it sound like i can apply 10 seconds even when the resistance is 0Ω,
but i assume that the internal heat in the megger,when the resistance is 10Ω
,for example,will be...
Hi.
I have a cheap megger that can generate:250DCV/500DCV/1000DCV.
The manual of it says:if the measured resistance is less than 1.5MΩ
at 500DCV position or less than 5MΩ at 1000VDC position,the measurement
time mustn't proceed more than 10 seconds.
I assume that there is a kind of current...
Oops,my mistake.So yes,I meant vertical.(y)
Thanks for clarify this detail.
I see that this line indicates half of the value
between two main vertical lines.(1mA,5mA,10mA).
Thanks to everyone for your help.:)
Thanks for the information fVm.
About the horrible diagram that you mentioned.
I know that it is very blurred and i wasn't meant
that someone will use it for any calculation.
I would like to know what the horizontal line in between indicates.
So i attached it for an example to my question.
When...
Hi Tony.
Isn't the curve slop(14D431R)that rise from 1mA-10mA: 60V rise (480V to 540V)?
One more thing about the U-I graphs of the varistors.
When the varistor graph is drawn as you may see at my attached photo,
Do the horizontal lines between the round numbers(marks with arrows at my...
Hi,klausST.
Yes,i attached the U-I graph from the datasheet in my question of the 14D431K MOV.
This sentence looks like a sentence from Psychometric test:)
You meant that the voltage across the led and across the MOV is depended on the current,right?
So if the 1.5MΩ resistor(on the right...
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
