Questions tagged [mov]

Metal Oxide Varistor - A circuit protection component which clamps voltage waveforms above some value that the particular device was designed to protect for. It is a sacrificial device and absorbs energy and accumulates damage over it's useful life, eventually failing. They come in different voltage and energy absorbtion capabilities.

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Using MOV to protect device for heater element

I have a heater element that is controlled by a solid state relay from main power. I know it is customary to place a MOV in parallel when switching inductive loads to clamp the voltage to prevent ...
realm god's user avatar
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Handling higher clamping voltage of IsoMOV - MOV/GDT Hybrid

I'm working on an ac mains control circuit and came across IsoMOV a new hybrid MOV/GDT for surge suppression. This appears to be a straightforward replacement for a standard TPMOV with additional ...
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Snubber circuit with MOV for relays connected in series

I have 5 identical relays (same specifications) whose working input voltage is 24V DC and output voltage is 220V AC. I have a problem that voltage spike due to large capacitance when switch turns on, ...
Choi Moonkee's user avatar
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How to spec a MOV resistor

I want to add a resistor before my MOV. The largest surge I will have will be 3kV. I came across this datasheet. If the most voltage my load can handle is 1kV surge, what will the resistor value be? ...
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LTspice MOV tutorial/help

I am looking at the availability of the pictured component on LTspice and cannot find it when I type it in the component library search. Please let me know the component symbol name or if I need to ...
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Variable Resistance in LTspice- Convergence problems + understanding the solver

I've created a variable resitance model in LTspice to simulate the behavior of a Metal Oxide Varistor. The variable resistance is performed with a behavioral source aas follows: ...
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Can this circuit limit power surges?

This circuit I had created based on MOV and a relay, it principle is: if a surge comes the MOV would get activated and should turn the relay thus the surge should be redirected. Notes: Input is ...
Hazardous Voltage's user avatar
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Problems with MOV (Metal Oxide Varistor) simulation in LTspice

I recently ask a question relating this topic because I was having problems with the spice models supplied by the manufacturers wich consists of a logarithmic power law: The problem was of the type &...
Santi Ospina's user avatar
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Location of Fuse and MOV

I have an AC module where the input is AC mains. I am also using 2 AC-DC modules. AC-DC module 1 5V output & AC-DC module 2 12V output Both these AC-DC modules requires fuses. I also want to place ...
Freshman's user avatar
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LTspice error with varistor model and impulse current test

I'm trying to use the TDK varistor spice models in LTspice and there are some things that don't add up. In the figure below you can see the actual equivalent circuit of the TDK model. I know that I ...
Santi Ospina's user avatar
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MOV parameters understanding and capacitance

I want to add a MOV to the input of my circuit. I came across the following MOV. The specs I require will be the following: Max voltage 300V AC rms Surge voltage 1.4kV Response time 8/20us I have ...
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Can MOVs draw lots of current at low voltage?

This circuit should open my fuse in case of an intentional overvoltage attack. (think as someone intentionally plugging 100V to the 24V input) Thing is I can't afford to have more than 45V to the rest ...
Alexsander Magalhães's user avatar
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Can electricity distribution transformers increase lightning surge current from 30 kA to 1500 kA?

I read somewhere that an average lightning strike is about 30 kiloamperes and lasts for a duration of 30 microseconds (but it may consist of number of sub-flashes so the total duration may be 0.2 ...
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How to protect a high-voltage output stage from very high transients

Usually in electronics, one can use MOV or TVS diodes to get rid of voltage transients. That's because most applications run at a voltage of 500 V or less. But assume I want to protect the output ...
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Identifying a MOV

I have a buddy with a St. Croix Lancaster corn stove with a control board in it that was taken out by a malfunctioning generator (the pellet stove was not even turned on, but like most semi-modern ...
Rusty Auxier's user avatar
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How do MOVs work for surge protection?

I'm trying to understand how MOVs operate but all my online reading is calling my understanding of electronics into question. The above diagram seems to be the typical layout of a MOV used for surge ...
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Right wiring for 3 phase 4 wire surge protection devices

I am looking for commercially available SPDs and came across two different options: Option - 1: Return path is earth and there is an MOV on all the lines. Schematic would look like this: Option - 2: ...
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Use of MOVs without fuse?

I understand the MOVs become almost short-circuit when input voltage across them exceed a threshold. But how does this protect the circuit behind the MOVs? Suppose the input power supply voltage ...
Saksham Jain's user avatar
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Does a relay with a capacitive load still require a MOV?

I was planning to install this Metal-Oxide Varistor (MOV) across a relay switch. But after I read about the use of MOVs for switches here, it seems to me that MOVs are useful only if the load is ...
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Help identifying MOV

Need some help in Identifying MOV ZNR E14221 RU068
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Confused about back EMF protection in maglock circuit

Straight upfront...electrical engineering is not my forte. However, I am trying to help a client with a particular issue and I'm hoping this community can provide some invaluable insight. They have a ...
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Is it possible to use an MOV instead of a flyback diode in a pulse circuit?

I am working on a small high-voltage pulse circuit to protect my animals. I have a question about the flyback diode D2 to protect the SCR. The flyback diode seems to waste a lot of energy between ...
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3 answers
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Scam? Does having this capacitor wired as shown provide any surge protection?

Bought this on Amazon as a dryer 240V SPD. I was trying to find out if this device is an outright scam. I found a similar post on here from several years ago but that did not answer my question. ...
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Can placing MOVs on a 240 V input ever be a bad thing?

The power supply of my home lighting keeps failing. So far I have had ten identical power supplies fail. Upon inspection the thing that is always damaged is the electrolytic capacitor after the bridge ...
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Triac driving motor with limit switch, needs protection?

I'm trying to drive a bunch of motorized ball valves from an ESP32. These valves have a 230V AC motor with one common wire, and two wires to set direction (open/close). When powered between common and ...
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How to add surge protection and over voltage protection for a smart switch SMPS

I am making a smart switch for toggling appliances with a 10 A relay using esp8266 as my MCU. I am using an isolated 3 W (5 V, 600 mA) SMPS. I have seen in some specifications about 2.5 kV surge ...
Daga Arihant's user avatar
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MOV failed due to lighting or OV on power line Feeder control

we have a filed failure of our product which is feeder controller as shown in below image. It installed in metal box. we have tested our feeder stand alone at 15KV surge and it compliance with 15KV. ...
4Mhz Crystal's user avatar
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Regarding connecting MOV and SMPS in parallel for electrical meter

We are working on development of a 3 phase electrical metering circuitry. All the 3 phases are connected to metering IC using resistor divider circuitry for voltage measurement (between phase and ...
Malyala Sai Kiran's user avatar
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gdt and mov surge protection

greetings fellow engineers, i came by to ask you for help, i'm building a circuit that needs to be as resistant to surges as possible. I did my research, and make to this circuit: as it is supply by ...
luis felipe Cardoso's user avatar
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Help in assessing the input mains circuit integrity

I've been working on designing a (220-380 VAC) 3/4 wire phase energy meter and in terms of metrology operation, things were working very well quite similar in terms of metrology if compared to a ...
Sultanpepper's user avatar
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What's the effect of parallel resistor and MOV?

What is the effect of connecting a metal oxide varistor in parallel with a resistor? Does the resistor make the varistor more responsive in case of a surge?
Valèt Quasar's user avatar
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Can a MOV properly discharge a X-Capacitor?

I created an AC-DC SMPS with a EMI filter that consists of a X-Capacitor and Common-Mode Choke. IEC 62368-1 requires that capacitors be discharged below ES1 (60V) within 2s of being disconnected. As ...
Charles Gervais's user avatar
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Digital input over voltage protection solution - varistor or TVS

I have to select the best safe solution to protect a 5V input. Below are four solutions that I have designed to protect my 5V input against over voltage using a varistor and a TVS. Different ...
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What is the 0V reference for MOV's input protection on power supply?

In some application notes for MOVs I see example usage in power supply design where each input line (N, L) from the mains are protected with a MOV to a ground voltage reference (as well as a ...
Johan's user avatar
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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&...
David Fear's user avatar
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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 ...
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Metal Oxide Varistor connection

How do I select the MOV for a multiple operating voltages. Consider the diagram below, when switch is in position 2-1 and 5-4 (both primary winding are connected in series), I can apply an input ...
launchin2space's user avatar
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1 answer
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How to place MOV when you have a center tapped transformer 127V 220V

I am building a circuit that gets power from AC. I have a center tapped 220V transformer, so I added a switch for 220V or 110V (the three wire sockets) I added two MOVs, one S20K230 for 220V and a ...
Augusto Mattos's user avatar
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What causes a varistor to have low resistance when connected to a board?

I was inspecting the control board on a non functioning opener motor, there are no visible blown out components. No skid marks. I went to testing conductivity on the fuse component, good across there. ...
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Metal Oxide Varistor Identification / Replacement? Component marking IOE241 99P

Could anyone identify the component shown in the image? It is marked 'IOE241 99P'. It is ~12mm in diameter. I believe it is an MOV. The image shows the location on the Power PCB it was removed from. ...
serpentinite's user avatar
1 vote
1 answer
307 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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Why is the maximum voltage of a surge, 6kV inside home wiring?

I was reading about the benefits and cons of series mode surge protectors vs MOV-based surge protectors for home use. First, why is the probability that a surge will exceed 6kV extremely low due to a ...
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286 views

Choosing the right TCO fuse temp. for varistor [closed]

What is the temperature value of a TCO (thermal cutoff fuse) which should be chosen in order to protect a metal oxide varistor (MOV)? (I mean cut the current to the varistor, before a catastrophic ...
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AC line surge protection with GDT in series with MOV

We often use GDT in series with MOV to protect AC lines as below. But i have Question as for 230V AC line and 275V Rated MOV - What Should be the Breakdown voltage of GDT ? Three options available :...
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Diodes used with MOV, which ones and why?

i was hoping to get some help identifying a component on an old circuit board that i have to repair, id also like to undertand the purpose of this combination of components. The circuit is on an ...
Russ Turner-Robertson's user avatar
5 votes
1 answer
3k views

How to test a MOV with no visible damage

As far as i know cumulative degradation occurs in a MOV when multiple surges appears in a circuit, A way to minimize this degradation is having multiple MOVs in parallel. This kind of damage can be ...
AmssmA's user avatar
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4 votes
1 answer
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Power input surge protection

I've seen power protection that uses: MOV (metal-oxide varistor) Inductor TVS diode Application Note: Transient Voltage Suppressors (TVS Diode) Applications Overview I didn't see any design guide ...
Hasan alattar's user avatar
2 votes
1 answer
2k views

Varistor + Inductor + TVS transient protection

I am struggling to understand how this circuit should work: I understand that inductor in this case is going to reduce the rate of changing current flowing through it, but I do not understand what is ...
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Calculating energy of transient/surge handled by metal oxide varistors (MOV) or surge suppressors?

As I get to know more about the MOV operation, there are more things needed to understand. My MOV (V420La20AP) has Varistor voltage of 680 Vrms (10%) at 1 mA, and maximum clamping voltage of 1120 V ...
BetaEngineer's user avatar
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1 answer
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What is Metal Oxide Varistor (MOV), meaning of its specification and how it protects circuit from over-voltages?

Hello, I have a circuit in which a voltage source is connected to some sort of RC Load. To protect this circuit , there is an Metal Oxide Varistor (MYN15-681K). The Pics of circuit and datasheet ...
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