Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [surge-protection]

Questions about protecting electrical devices from voltage spikes.

328 questions
31
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4 answers

Why is daisy-chaining surge protectors not recommended?

I know MOVs inside surge protectors degrade over time, but I also see manufacturers putting notes on the box that the protection warranty is void if I daisy-chain surge protectors. So questions: Is there an estimate of what the life of a MOV is…
sekharan
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3 answers

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 the operation principle.
Roman Simonyan
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14
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2 answers

Suicidal ASUS power brick?

I was playing around disassembling an Asus laptop power brick (19V, 4.74A) and came across this strange arrangement in the circuit, where just after the bridge rectifier, there is a MOSFET (Q1, N channel) that can make a <1 Ohm connection from the +…
parkside
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12
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3 answers

What would it take to make a PS/2 keyboard interface hot-swap?

A long time ago, I had to service some of the early Compaq Desktop PCs. They used to have fuses on the motherboard that blew when a customer hot-plugged a keyboard. I found this when googling on the topic: The keyboard or mouse should not draw more…
drudru
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12
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2 answers

ESD strike on exposed circuit ground pin

I've designed a circuit for a battery operated device which has a USB connector externally exposed for charging and data transfer. It is a non-standard, dockable USB connector with no shield connection available and the entire circuit is housed in a…
sbp9674
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Can all surge protectors wear out, and how would you know if this is the case with the surge protector you have?

This question follows from this other question where the OP mentions that: I know MOVs inside surge protectors degrade over time Based on this it seems that surge protectors eventually deteriorate past a point where they do not provide (expected)…
user64167
11
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2 answers

Difference between ESD and TVS diode?

What is the difference bweteen TVS diode and ESD. Though both of the functions are the same, which do we need to choose for what application?
Selva97
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10
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Why are modern telephone lightning arrestors less prone to (rectification) RFI problems than old ones?

I was reading about telephone lightning arrestors in my ARRL RFI Book (first edition, copyright 1998), in chapter 9 "Telephone RFI" (by Pete Krieger, previously WA8KZH, now K8COM) and on page 9.6, the following is stated (emphasis mine): The…
MicroservicesOnDDD
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10
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Relay protection when proper TVS at load cannot be implemented

I'm currently developing a product which has a simple SPDT relay that can be controlled by an operator. To the end-user, only the common, normally open and normally closed contacts are available. The relay is driven by circuitry in our device, which…
Chi
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10
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Zener Diode for overvoltage protection

I am considering to use Zener diode for over-voltage protection for a digital input pin. The absolute maximum rating for the typical IC pin is given as from (GND-0.3V) to (VDD+0.3). I can use Zener diode to limit voltage below VDD. However, the…
Steve
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9
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2 answers

Transient voltage suppression diode not doing its job

I have a circuit which works on 21V DC and draws 3A maximum current. I need to get it tested to IEC 61000-4-4 and 61000-4-5 standards which are surge immunity tests. I use a UL certified switch mode power supply to power my unit. The supply…
mic
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8
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4 answers

Is it Safe to Plug an Extension Cord Into a Power Strip?

Just a bit of context, I am a technology enthusiast. I love everything from software to hardware, Windows to Linux, Computer to Phone, and everything in between. So, I wouldn't be surprised is my electrical usage exceeds 50% of the entire household…
user213595
8
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3 answers

Connecting TVS before or behind Ethernet transformer?

I looked at several designs and recomendations. Why do TVS diodes sometimes connect before and behind transformer? What are the pros and cons of connecting before or behind?
AndreyB
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8
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1-Wire DS2480B overvoltage and ESD protection

I'm designing a series of 1-Wire components for my SmartHome Bus and use the DS2480B as Busmaster. Because the cable I run around the house has 3 wires (24V, 1-Wire, GND), I'd like to protect the DS2480B from overvoltage caused by accidentally…
final
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7
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Can lightning strike into the phone line damage electronics in the house through the ADSL modem?

I was always wondering about the following: If lightning strikes directly into the phone line outdoors, can the excess power coming from the phone line jump over the switching power supply of the ADSL modem into the mains in the house and damage any…
adamsfamily
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