What is mov and how Do i implement in my power circuit...

[yusuf]

hi friends again :

what is MOV and How do I implement in my power circuit... and how do i choose required values Of MOV for my projects....

 

[Reloadron]

Read this link in detail. Once you understand what a Metal Oxide Varistor is then:

SELECTING THE PROPER MOV VOLTAGE RATING:
1. Determine the required voltage rating.
First, the maximum steady-state operating voltage of the circuit must be determined. Care must be taken to use the upper tolerance limit of the voltage source, e.g., for a 220VAC line,a 10% high line condition should be assumed, resulting in 242 Volts. Once the level is determined, refer to the column in the data table headed "Maximum Continuous Voltage" and select a group having the nearest greater value to this level.

Read this link.

Ron

 

[yusuf]

the model number of my MOV is SVC 431-14.
So from this model number how should we know the rating , voltage etc...

 

[Reloadron]

We don't. I have no clue who manufactured it. I have no data sheet on it.

If you had the tools needed you could place a voltmeter across it and a mA meter in series with it and apply a voltage and note where it begins to draw current as you increase (slowly) the voltage across it. This is where a good curve tracer device comes in handy.

Ron

 

[crutschow]

We don't. I have no clue who manufactured it. I have no data sheet on it.

If you had the tools needed you could place a voltmeter across it and a mA meter in series with it and apply a voltage and note where it begins to draw current as you increase (slowly) the voltage across it. This is where a good curve tracer device comes in handy.

Ron

I recommend adding a resistor (say 1k ohm) in series with the MOV when you do the measurement, to minimize zapping anything.

 

[Reloadron]

Carl made an excellent point. When I run stuff like this I use a curve tracer and without thinking add the series resistance.

Ron

 

[cachehiker]

We're always looking at mov's, never in detail though. We lack the equiment to do so. Some of the samples we get have clamping voltages that creep up close to 1.0KV. We hit a sample with the hypot machine on a 2 second ramp at 1mA and 2mA trip currents. It has always indicated a breakdown voltage that closely corresponds to the rated clamping voltage. If it's not a well known brand with a datasheet, we then conservatively estimate the Joule rating from the size of the mov.