Questions tagged [varistor]

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17
votes
3answers
2k views

Varistor? Purpose and principle

In the AL9910 LED driver datasheet it shows a part, which I assume is a varistor, is it so? Varistors are shown to be connected across L and N lines, but here it is connected in series. Please explain ...
11
votes
1answer
3k views

Potentiometer vs Varistor

What is the main difference between and potentiometer, rheostat and a varistor? And how do the application of the three in a circuit differ? Or to be more concise, in a variable power supply why ...
8
votes
3answers
5k views

What are some common applications of the MOV? (Metal Oxide Varistor)

The owner of a broken washing machine recently asked me to examine a damaged circuit board he had found inside. Using the schematic I was able to determine that the charred area formerly contained a ...
6
votes
2answers
7k views

How to choose the right Metal Oxide Varistor (MOV)

I would like to protect the input of a transformer against high voltage surges but I don't understand how I have to proceed to choose the right MOV despite what I read so far about them. Below is how ...
5
votes
2answers
2k views

Help identifying a varistor?

Need help identifying a component that I think is a varistor. It is burnt so it appears black. The circuit is part of a control module for the headlights and keyless entry on a Lincoln. I want to ...
5
votes
1answer
466 views

MOV Characteristics

I need to select MOV for my application. Vin max=520Vrms Surge Voltage= 4000KV as per IEC61000-4-5, 8x20us waveforms. So my calculation is $$ \text{Surge Current}={(V_{transient\_max}-V_{clamp}) \...
5
votes
1answer
541 views

What component has the reference designator RY?

I found a component designated RY8015 which I don't recognize, shown on the photo below on an LCD TV PCB (the bulb-like part next to a green radial varistor). What is it called? What is its design ...
4
votes
2answers
4k views

How can I compare a TVS diode with a varistor?

For a 120Vac line protection element, comparing this TVS diode: With this varistor: The immediate differences I see are: The varistor is marginally cheaper The varistor specifies a maximum working ...
4
votes
2answers
1k views

Is a varistor basically two diodes in series, with opposite polarities?

The typical curve for current vs voltage for a varistor: looks a lot like the 2 reverse voltage regions of a normal diode: Is this equivalent the following, and if not, why not? simulate this ...
3
votes
1answer
505 views

Are external components required for HLK-PM01?

Apologies in advanced as this is kind of a vague question and due to my lack knowledge in this specific sector. I'm designing a circuit using a HLK-PM01 as the power supply which is a 3W AC-DC ...
3
votes
1answer
445 views

Creating a temperature-dependent solar cell in LTSpice (using varistors)

I'm currently working on my master thesis and therefore need to simulate a solar cell in LTSpice. I've already modeled and simulated some examples with constant values. But for a more accurate model, ...
2
votes
1answer
1k views

Is this a varistor?

Can someone id this green part? Z5V 104Z 500V I think maybe it's a varistor (like the blue one in the lower-right of the image) but haven't been able to find a replacement.
2
votes
1answer
2k views

GDT in series with varistor

I often see GDTs are used in series with varistors, like this E100 is a 1500V/10A GDT, and RV100 is a 1.1KV diode varistor. For this circuit, I have two question What's the benefit to combine them ...
2
votes
1answer
294 views

Energy dissipation and current decay in this circuit

I have a circuit that looks like this : A 200 A current controlled power supplies delivers the current to a coil (with inductance ~ 5 mH) when the MOSFET is open. The varistor is there to clamp the ...
2
votes
2answers
539 views

How to reduce a pulse voltage maintaining a high impedance?

I have one pulse with 200ns and 60 V. I have to reduce this voltage until 10 V min because of the monostable multivibrator. After this, I will extend the pulse with a monostable multivibrator and then ...
2
votes
2answers
1k views

Thermally protecting a varistor

I am designing a circuit that has a nominal 24VAC input. This circuit is protected by a 4A Fast-Acting fuse. I would also like to insert a transient voltage surge protection. For achieving that, I am ...
2
votes
1answer
349 views

Varistors in three phase application

From this Reference Design, I have the following inquiry: Usually in three phase applications I see varistors connected between phase to phase, or between phase to ground. In the reference design, the ...
2
votes
2answers
178 views

How much buffer room is required for a varistor?

I am working on a circuit board design that uses a fuse resistor for protecting from short circuits and a varistor to protect from over voltage. The board is a simple power supply of only a few watts. ...
2
votes
2answers
3k views

Connecting varistor and surge arrester in series

I have a doubt about proper values of MOV and SAR when they are connected in series as suggested in Epcos app notes (see below Fig. 12). For the 230 VAC mains they recommends SAR of 470 or 600 V, but ...
2
votes
2answers
672 views

3 LEDs / 1 POT - fade each LED in turn as POT is changed in value ?

I'm looking for a simple (hopefully !) circuit which would allow a variable resistor to control the brightness of three different coloured LED's. As the variable resesistance is changed in value first ...
2
votes
1answer
108 views

Suitable Substitute for this Varistor MDC Z750 / 40

I am in the process of restoring a vintage EZGO Golf Cart and have came across a component I am unable to locate within the generic golf cart electrical diagram. This varistor is from a 36 volt DC ...
1
vote
3answers
6k views

Help identifying a varistor

Hi I am trying to identify what I think is a varistor. The problem I am having is the markings, other than the voltage don't seem to corrolate with anything. So I'm not sure if it is a varistor or if ...
1
vote
2answers
514 views

What kind of elements are these?

I disassembled a LED lamp and it's circuit. My intention is to rebuild that circuit within EveryCircuit app, to understand how it is working. On this circuit I found two elements that are rising ...
1
vote
1answer
117 views

Identify unknown disc-shaped component - markings include VF10 0471K

I am trying to identify this piece, which I believe is a varistor, though I'm not sure. It comes from a Samsung rice cooker. I have attempted numerous google searches on the markings, but I have so ...
1
vote
1answer
44 views

Protecting a switching regulator in a 12v automotive system

I'm using a MaxLinear XRP7659 as a 12v -> 5v regulator in my design. The circuit has an average power usage of 80mA @ 12v and a maximum usage of ~500mA @ 12v. I have a 750mA fuse on VIN, along with ...
1
vote
1answer
326 views

Varistors set to ground or case by isolated ground/case

I have a isolated ground from the case in my device. The Supply Voltage is +24VDC with Ground and separated CASE, so no safety issues. On any signals coming from the case (Plugs) I put varistors, but ...
1
vote
1answer
244 views

Is this a varistor? WP 270M

I can't figure out whether it's a varistor or any other non polar capacitor. Please also suggest how to test it.
1
vote
3answers
821 views

Maximum fuse rating before a MOV (varistor)

I just watched some scary videos of MOV's catching fire and I've flee'd here to ask you guys for help. I understand that it's a good idea to put a fuse in front of a MOV, considering it fails short-...
1
vote
1answer
739 views

Should I use both a MOV & a flyback diode for a very high power DC motor (7560W)?

I couldn't find a circuit online that uses both so I figured I better ask those who know more than I do if this would be a mistake or not. Thanks for your help
1
vote
0answers
135 views

Component identification - Power supply circuit component exploded

I am fixing the power supply board of a big mobile sound system. Skytec PA-200 - sadly I could not find any schematics or more information on it. Unfortunately not only an electrolyte capacitor but ...
1
vote
1answer
70 views

Can I use a back to back Zener as a flyback diode for an AC coil?

I am using the below AC electromagnet to switch on/off a pneumatic system. (It is a pneumatic actuator. I think that is what it is called.) The issue is, when I turn off (disconnect the switch) the ...
1
vote
0answers
169 views

Replacement for TVR 10561 varistor

I am trying to repair the power supply of my PS4. It looks like the fuse has blown out with the TVR 10561 varistor. I can't find this varistor online and I am looking for a replacement. The TVR 10561 ...
1
vote
1answer
85 views

Is this a capacitor or a varistor? How can I figure out specifics?

Is this a capacitor or a varistor? How can I figure out specifics?
1
vote
2answers
108 views

Why would bridging a varistor with the multimeter leads on any setting have caused the unit to turn on?

So I've been working on fixing this window AC unit for a while, and when I started I knew next to nothing about circuits. At present today, I know a bit about circuits -- enough that i at least know ...
1
vote
0answers
849 views

Power Supply Fuses and Varistor

I wish to build a little decent power supply for my IoT devices, would like also to implement more protection from the live 230V AC side and I decided to put a fast blow glass fuse in a nice holder, ...
1
vote
0answers
159 views

Trying to identify varistor values off an ancient power supply

Was tricky to get a photo with the markings visible, but as best I can tell the markings read... H L1 1502 ...The scoring down the middle is from where I ...
1
vote
2answers
272 views

varistor with reverse operaton

Varistors are known to use for over-voltage protection, as they have high electrical resistance at low voltage which decreases as the voltage is raised.(wikipedia). But is there any electrical ...
0
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2answers
2k views

The capacitance parameter in varistor data sheet

What is the meaning of the capacitance parameter in the datasheet of a varistor? For example: I have noticed that 7mm 430 varistor voltage(07D431K) and 14mm 430 varistor voltage (14D431K) have the ...
0
votes
2answers
147 views

Varistor - Place before or after the fuse? [duplicate]

What is safer? Before or after the fuse? In my case the varistor is 10mm, 275Vrms, and it is currently placed after a 250Vac, 7A, 20mm glass fuse. Would the varistor blow the fuse easily if placed ...
0
votes
2answers
820 views

Placement of varistor with respect to fuse

My design includes a pretty standard AC/DC converter powered by mains for intended use at home. For overvoltage and overcurrent protection, I am planning to use a combination of varistor and fuse ...
0
votes
1answer
4k views

Does a varistor have anode or cathode or polarity?

Below is a MOV varistor: Does a varistor have anode or cathode or polarity? Can I connect the legs in any way or does it have an orientation like diode?
0
votes
2answers
79 views

Electric stove heating element and switches

I am having difficulty in understanding how heating elements and switches work to control how much heat is dissipated in the element of electric stoves or other similar settings. From one perspective ...
0
votes
1answer
938 views

AC/DC power supply: help to choose fuse, varistor and/or TVS diode

I'm going to use this 12VDC AC/DC power supply . It is the first time that I am going to use one and I have some questions about over voltage protection and peak current protection. These are the ...
0
votes
1answer
217 views

Help identifying Components

I need help tracking down 2 replacement parts. From what I know they are 1 Varistor and 1 Pico Fuse. Could anyone confirm that and tell me what I should be looking for to replace them. Googling the ...
0
votes
1answer
850 views

Does SSR with DC Motor still nead back EMF protection

I plan to use a solid state relay to control a couple of small 12 VDC motors. One is 12V, 12Watt (1A) and the other is 12V 11amp peak. The SSR can handle 15A DC. Some of my inputs (different part of ...
0
votes
2answers
46 views

Help Needed to Identify/Source Varistor S14 K140 0023

Could someone please advise on how I interprate the codes on this Varistor below.. I'm almost there, I can find the S14 / K140 on RS Components, But im unsure about the last 4 digits. RS Website PN:...
0
votes
1answer
82 views

Varistor equivalent

I am repairing an old Marantz stereo amplifier and have come across a varistor MV11Y that appears to be the issue. Is anyone able to advise/send me the data sheet for this varistor or perhaps let me ...
0
votes
1answer
62 views

Help identifying a varistor (on a shredder PCB)?

I am trying to identify what I think is a varistor. The markings are : "9 / MVG" and "10K431". I think "10" is the diameter, "K" is the tolerance and "431&...
0
votes
1answer
55 views

Transient current value

I am working on a SMPS and wanted to size a varistor at the input to protect the rectifier against transient overvoltage (let's say a 1 ms surge). However, by looking at datasheets the maximum ...
0
votes
1answer
477 views

Do I need to remove the varistor from the circuit to check its validity with DMM?

When I looked up how to measure varistors, I found that the varistor's value should be 0L ohms (Over range, infinite resistance) when measured by a DMM set to test resistance, to indicate its validity....