Questions tagged [varistor]

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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 ...
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41 views

Varistor and TVS diodes in series

In the picture below, the input of the rectifier is 690VAC max, so the DC output can reach up to 1kVDC. The DC output goes to a low power DC/DC Converter. In the picture on the left, I'm using a ...
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50 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 ...
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50 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....
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33 views

Identify a varistor

I'm trying to replace these two varistors from my maytag dryer. I'm not quite sure what party they are. They look like epcos/tdk brand but not sure what the s20 k275 11 08 means, Or the other symbols. ...
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47 views

Can a Varistor be used as a Capacitor?

Let's say to protect a line (DC, signal or power), I place a varistor between the line and GND. Basically to avoid large surge of current. Then, it happens, that on the same line, I also need a 1000pF ...
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2answers
86 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 ...
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17 views

Relay for rollershutter motor

A few years ago, I build a controller for our garden door rollershutters (2x 2m wide), 230VAC 2xL-N controlled. In some initial tests, the inductive load killed the cheap mechanical relays found on ...
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1answer
69 views

Why does the high capacitance of a metal oxide varistor affect sensors and signal sensitivity?

I want to know why the high capacitance of metal oxide varistors affects sensors, signal sensitivity. How does capacitance affect sensitivity ? If we add a low capacitor in series will the total ...
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42 views

Can we use tvs and mov together for thruster?

I want to know if we can use both tvs and mov varistor together ? What will be good for thrusters ? And placement between esc and thruster or before esc? Update: system voltage is power supply ...
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140 views

Why often is used a varistor 7D471K for 220-240vac surge protection rather than a lower nominal voltage one?

In my "supposedly" surge protected power stripe there is a varistor for surge protection configured to simply short-circuit the entrance wires in case of surge. Checking the model it's a MOV-7D471K ...
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1answer
42 views

Varistor in a DC circuit

I'm employing a Varistor in a simple circuit that will be used in a car. The Varistor is there to ensure that any load dumps / vehicle transients will not result in catastrophe for the circuit. My ...
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1answer
72 views

Calculation of varistor parameters for AC line protection

There is a task to choose a varistor to protect the AC circuit, controlling several coils of magnetic starters. Characteristics: Mains voltage 230-240V AC Frequency: 50Hz Starting current of coils ...
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1answer
64 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 ...
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1answer
239 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 ...
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2answers
372 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 ...
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1answer
96 views

Trying to ID this component & where to get a couple of them? Is it a varistor?

Here's a photo I made to show back and front of this thing. I think it's a varistor. The main body is roughly 8.5mm in diameter. I straightened the two legs but I think they are SUPPOSED to have ...
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1answer
37 views

Need some help Identify a Varistor

I had a either a surge or a part failure cook a few components on board. The board is rather old from a discontinued product. On the board the only components I've not been able to identify that need ...
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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 ...
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1answer
297 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, ...
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2answers
147 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. ...
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1answer
106 views

What is this solar power RC circuit doing?

I am a CSE student working on a project. We are using a solar powered microcontroller. The solar panel's power goes through a fuse and an RC circuit with a varistor to the charging system. What ...
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1answer
622 views

Why does my varistor cause my fuse to blew up?

I have made the following circuit (copied from a very similar picture on internet): At one side of AC/DC I put a normal fuse. The MOV is a 14D391K 14K391 390V varistor diameter 14mm AC 250V DC 320V ...
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2answers
2k 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 ...
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1answer
214 views

Can Orcade (PSPICE) actually simulate MOV(Varistors)?

I am using Cadence-Orcade Lite. In it I have a circuit in which I want to note the behaviour of varistors (MOV, PSPICE models exist in Orcade for various varistors). I am using LS40K680QP/EPC Model ...
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0answers
561 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, ...
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1answer
187 views

Help with identify varistor

Need help identify this varistor. Been trying to figure it out since 5 pm of yesterday. Cannot find anything on it. Any help is greatly appreciated.
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2answers
1k 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 ...
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1answer
78 views

Discharge of a coil powered by parallel transformers

I have the following circuit: I basically have 2 transformer, one is 230V-8V the other one has a ratio of 1:1, so 230V on the secondary. I'm rectifying the two signals with two full bridge ...
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3answers
563 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-...
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1answer
662 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 ...
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1answer
2k views

Identify Varistor TVR 20471

I got this broken Varistor from an Eaton3S 550VA 300W UPS. Marked TVR 20471* I have tried my best to find a replacement but I can't find a similar one. Any tip or recommendation for a similar one that ...
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2answers
5k 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 ...
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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 ...
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1answer
275 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 ...
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155 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 ...
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1answer
528 views

varistor curve and voltage meaning

Could I get an explanation for these datasheet definitions for a varistor? 1) Max. applied voltage. 2) Min varistor peak volts. 3) Max varistor peak volts. 4) The clamping voltage is known to be ...
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36 views

VI curve varistor and compere between varistor and arrestor

why we need to connect arrestor in parallel with varistor in some circuit ? and we know both is work to protect against high voltage? like this pic.
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156 views

Blown varistor after connecting UPS?

I have a pellet burning stove and the manufacturer provides for two options for battery backups. One is an inverter and deep cycle battery that can run the device for a few hours, the other is a UPS ...
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1answer
3k 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?
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169 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 ...
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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.
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179 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 ...
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1answer
620 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
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684 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 ...
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3answers
5k 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 ...
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2answers
1k 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 ...
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377 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 ...
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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 ...
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2answers
473 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 ...