Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

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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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. Apparently this device was originally sold as a "power…
Jason P
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Using a TVS diode instead of, or in addition to a MOV for AC line protection?

For 220 V AC mains voltage, is it good practice to replace a 300 V MOV with a 300 V bidirectional TVS diode (like in here http://www.littelfuse.com/products/tvs-diodes.aspx), or connect both in parallel? Are there any points that need to be…
downthewire
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1977 GE 6RS20SP9B9 - what the heck is this component?

Ok so, ordinarily I'd not ask a "what is this" question, but this component really has me scratching my head - both at its function in the circuit and how it is constructed. Anyone know what a GE 6RS20SP9B9 axial device, circa 1977, is? The only…
rdtsc
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Clamping Inductive Kickback in AC Circuits

I want to eliminate/clamp the inductive kickback that would result from turning off a large inductor, such as a relay or a transformer. In a DC circuit, I would use a diode to flywheel the current. But what do I use in a line voltage AC circuit? Is…
mcu
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Why not use only a MOV as a snubber for relay control of AC motor?

I'm building a circuit to control an AC motor using a relay. Since the motor is an inductive load, there will be a voltage spike when the relay opens. It seems that best practice for dealing with this voltage spike is to connect a capacitor across…
avl_sweden
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Relay control of AC motors, handling turn-off kickback

I've been researching how to control a smallish AC-motor using a relay, and more specifically, how to turn an AC motor off using a relay. This is a subject that has been up many times at this site, but the answers given vary quite remarkably. The…
avl_sweden
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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 protection. When surges occur, the resistance…
Mick
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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 inductive. I will turn on/off an SMPS with this…
cm64
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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 internal and so not detectable by visual…
AmssmA
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Placing TVS or MOV or Transzorbs for a very basic protection

This is a question for a general scenario I encounter. So I will not be specifying much details besides the voltage level, cable length/type and the power supply type. Imagine a sensor placed outdoors is measuring some air parameter and it is…
GNZ
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MOV as a snubber

I'm trying to design a solid state circuit breaker using bi-directional switch modules with IGBTs. (Rating: 3phase: 690V AC, 1000A) The problem here would be the transient voltage spikes across the switch and the solution would be to use some kind…
Pujitha
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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}) \over Z_{source}} = {(4000V-1500V) \over…
Bharav
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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 for the inductor selection, so I choose 1 A…
Hasan alattar
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Best practice for Lightning/Surge Protection on PCB

What is best practice/recommendation when I want to protect against lighting/surge? More specfically, my application requires passing the following test: "ANSI/IEEE C62.41---1.2/50 microsecond (uS) — 8/20 uS Combination Wave. Peak voltage is…
hassan789
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Relay protection with MOV and RC Snubber

I am going to build a protection circuit for a 240 volt pump motor. It is believed that when the relay cuts out the motor generates voltage back into the relay and burns out the contacts. It has been suggested (on this forum) that a MOV and RC…
user40681
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