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Questions tagged [varistor]

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0
votes
1answer
27 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 ...
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 ...
0
votes
1answer
27 views

Help finding a replacement varistor [on hold]

Hello, I’m having problems trying to find a replacement for this burned out Mov. The only details I can read off the picture are 05D391k (no manufacturing detail or logo to trace) It is part of a ...
3
votes
1answer
73 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
2answers
65 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. ...
0
votes
1answer
66 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 ...
0
votes
1answer
119 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 ...
4
votes
2answers
785 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 ...
-1
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0answers
72 views

Choosing Varistors for 61000-4-5

I would like to know what kind of surface mount varistor I need to choose to pass IEC 61000-4-5 Class II which is 1kV for a low voltage (24V dc) circuit When you want to choose Varistors or MOV you ...
0
votes
1answer
88 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 ...
1
vote
0answers
149 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, ...
0
votes
1answer
72 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.
5
votes
2answers
604 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 ...
0
votes
1answer
52 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 ...
1
vote
3answers
196 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-...
0
votes
1answer
399 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
636 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 ...
4
votes
2answers
2k 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 ...
4
votes
2answers
566 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 ...
2
votes
1answer
236 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 ...
1
vote
0answers
126 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 ...
0
votes
1answer
313 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 ...
0
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0answers
30 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.
0
votes
0answers
117 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 ...
0
votes
1answer
2k 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
1answer
136 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 ...
2
votes
1answer
758 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.
0
votes
0answers
90 views

Mysterious component uniting separated Grounds

I can't find a datasheet for this component, i've looked everywhere... RA20 66DR (could be RA2D or RA2O, same results, no datasheets..) This little fellow is cracked and its DC resistance ...
1
vote
1answer
109 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 ...
1
vote
1answer
424 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
0
votes
1answer
488 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 ...
1
vote
3answers
3k 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 ...
0
votes
2answers
974 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 ...
1
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2answers
268 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 ...
7
votes
3answers
4k 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 ...
1
vote
2answers
377 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
159 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 ...
2
votes
2answers
2k 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 ...
0
votes
1answer
93 views

Fuse Question and Surge Protectors

I am doing a DIY PDU project for my college using an Arudino and I have 8 16Amp relays that are controlled via the board. I want to make some sort of surge protector for it as well. Basically I want ...
5
votes
1answer
241 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}) \...
10
votes
1answer
2k 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 ...
5
votes
1answer
325 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 ...
2
votes
1answer
1k 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
2answers
928 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
2answers
527 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 ...