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Questions tagged [fault]

The tag has no usage guidance, but it has a tag wiki.

1
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1answer
35 views

Searching for 'ground fault' on DC power supply, 0VDC to ground

We have 3 chargers for DC power supplies (125VDC battery banks) at our facility and had a contractor come in and test them. They said there is a 'ground fault' on 2 of them in their report. The only ...
0
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0answers
60 views

Faults in a RLC circuit

Suppose we have a classic RLC circuit, in series and with constant voltage. Let's suppose that the resistance, the inductance and the capacitance can be affected by a fault. For which components can ...
0
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1answer
33 views

Power strips show fault in some outlets but not others

I'm not sure if this is on topic or not, but I thought I would ask. I have a few power strips (surge protectors) in my house that I use for computers, TV, etc. Some of these have a "fault" or "surge"...
1
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0answers
44 views

Calculate ground fault current leak on human contact

I am sure this is very very simple and probably realy dumb but I've been banging my head for hours and can't figure this out. Or find an answer on google/books for that matter. Even with the diagram ...
1
vote
1answer
60 views

Can a ground fault be caused by something outside the home?

Yesterday afternoon, I had a GFCI switch trip. It would not reset. I figured I had a ground fault. I left the home for a few hours and after I returned I was able to successfully reset the GFCI. The ...
2
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2answers
95 views

If neutral line touches the live wire, how to protect the devices connected due to neutral fault?

If the neutral line accidental touched the live wire, then due to momentary surge the home appliances connected gets damaged, what are the ways to protect the devices. Would RCCB be helpful to protect ...
1
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1answer
62 views

Substation grounding

I am trying to understand a grounding system for substations, fault current is something I am not getting. For example, for a small substation with some transformers, if there is a fault in the system ...
0
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2answers
114 views

X2 capacitor. Test if failed open

I am looking at a small board in a paper shredder (it does not work). If I apply AC power and measure AC voltage across the X2 capacitor (I think it acts as a voltage dropper for the low voltage ...
0
votes
1answer
71 views

How to build (from scratch) a GFCI Circuit? [closed]

I am looking to understand what is the circuit inside a Ground Fault Current Indicator (GFCi). What does the circuit look like? Simple google search is not yielding good results about the guts of it.
0
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1answer
69 views

Best way to locate a 4k stray resistance between 2 bus lines in a PCB?

I have a faulty PCB which is showing an unexpectedly low resistance between certain pairs of bus address lines. I'm measuring a little over 4k ohms between these bus lines, but according to the ...
0
votes
1answer
141 views

Linear voltage regulator failure?

I've been building USB powered audio DAC circuit which is using multiple LDO voltage regulators. I discovered one of the regulators, namely TPS79333, which is responsible for supplying 3.3V to ...
0
votes
1answer
40 views

Purpose of using per unit when calculating faults?

I read a book about power system faults - they all use per unit. They show examples of generators supplying motors through a transmission lines. They convert real voltages, powers and resistances into ...
1
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2answers
112 views

RS485 Multidrop Issues

I have an application where we use RS485 to communicate messages to a series of LED Displays on the bus. Our first version of the board seemed to work fine with no problems, however we have made a new ...
1
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3answers
130 views

Not understanding why in overcurrent protection only a certain section will isolate (why not the whole system)

I'm having an issue understanding a simple concept for faults. I understand the principles of how the relays cause the circuit breaker to open etc when a larger current goes through them to provide ...
0
votes
1answer
36 views

Voltage fault injection possible on switch output?

I am required to check that the software in a system correctly handles a fault condition from a high side power switch. The switch has a current sense pin which sends a voltage back to a ...
0
votes
1answer
28 views

Fault modelling stuck at fault for combinational circuit

A circuit has n inputs and n outputs. It is implemented only using AND, OR and NOT gates. Further, there are no fan-out branches. What is the number of s-a faults that remain after fault collapsing? ...
0
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1answer
76 views

Why does one of my HiFi speakers only start working after several minutes? [closed]

not sure if this is an EE question, it's the closest SE site I could see? I have a Sony separates mini-system (HCD-SD1) I was given; it's quite old now but good. Except that for a while now, when I ...
1
vote
1answer
324 views

HDMI triggering the Ground Fault Circuit Interrupters via Projector

Overview: A colleague of mine took her HP laptop from Canada (19.5 V, 1.4 A DC rated) to work in Brazil and experienced ground fault trips on the outlets when she connected an HDMI to a projector ...
0
votes
2answers
401 views

Single-Phase-to-Ground Fault doubts

I'm studying Fault Analysis Using Symmetrical Components and I have doubt over the single Phase to Ground Fault. On the book is written that generally Is and It are equal to 0 during a single-phase ...
1
vote
2answers
357 views

Ordinary Differential Relay Problem

The answer given in my workbook to the above problem is A. The things I was able to point out secondary c-phase current = 300A and other secondary phase currents = 0A since the entire current ...
0
votes
3answers
2k views

What causes a faulty Linear Voltage regulator to output wrong voltage [closed]

I made a circuit where I needed DC 8v supply. I was using a KA7808 to regulate the voltage. While testing the voltage regulator unit, I identified that the Regulator IC might be faulty because I was ...
2
votes
1answer
89 views

Why symmetrical component analysis is necessary for fault calculation?

If a 3 phase fault occurs the direct axis sub-transient reactance is sufficient to calculate the fault current. But in case of an unbalanced fault it is not. Taking the example of Line to Ground ...
0
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0answers
55 views

Unbalanced Fault Problem

I have attached the image of a theoretical question with its explanation given in my book. can anyone please explain this ? I am not able to start from anywhere so I can't show my work. I am posting ...
0
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2answers
473 views

How do solar panels affect the short circuit fault currents of a network? [closed]

As title suggests, I'm trying to find out how adding PV, both residential and solar farms, have an effect on the short circuit fault current of a network. I wasn't given much info to go off, so I am ...
2
votes
5answers
236 views

How can I protect a 12VDC power source from high-resistance shorts? [closed]

I have a pickup truck with a 3kw AIMS inverter-charger. It is wired with 4/0 welding cable (for both positive and dedicated neutral back to the alternator), and I installed a block with a 300A fuse in ...
0
votes
1answer
59 views

Historical Addressing Modes/Conditions that Complicate Page Fault Handling

I was reading this linked question and the following paragraphs stood out to me: For example x86 and 68000 had instructions which access memory two or more times. Each memory access could cause a ...
2
votes
0answers
103 views

Why won't LED light? [closed]

So I'm attempting to diagnose what's wrong with my daughters light up fidget spinner after she dropped it on the floor (and if possible fix). But I seem to be having a failing at electronics 101 and ...
-1
votes
1answer
63 views

how decreasing ground fault resistance decrease the touched voltage?

Fault current = supply voltage / fault path R. Assume live conductor of 230v touches the equipment metal frame. 1) assume R path through grounding electrode 25 ohm I= 230/25=9.2A 2) R=3 ohm I=76....
3
votes
1answer
1k views

Ground fault protection for fault on delta side of a wye-delta step down.

I have a distribution circuit with a primary 4-wire 21 kV and secondary 3-wire 12 kV circuit. The two winding transformer is a (grounded) Wye-(closed) Delta transformer. I know that if I have a ground ...
-6
votes
1answer
106 views

Repairing Television in Protect-Mode [closed]

My 5-year-old television (Philips 32pfl5405h/12) stopped working two weeks ago. It seems to be in protect mode as its standby LED keeps blinking three times. I pulled the plug and left it for a week -...
1
vote
0answers
435 views

When are positive-sequence and negative-sequence equivalent impedance the same?

One of the topics we covered in an introduction to power systems class was using zero/positive/negative sequence networks to analyze faults in networks. For many problems, this requires setting up ...
-1
votes
0answers
58 views

Shock From HDMI Plugged Into TV [duplicate]

I recently bought a new TV and I noticed that when I touch the end of the HDMI cable I get a shock even when the TV is off (this also happens with the VGA -> Mini DP cable). I can only feel the shock ...
0
votes
2answers
1k views

advantages and disadvantages of using a microcontroller vs dedicated switching controller for a switching power supply?

Trying to build a constant current power supply for a laser diode here. I don't think I can use an off the shelf one because of the large 10A max current and because the current has to be controlled ...
3
votes
3answers
669 views

Class A amplifier asymmetric distortion mystery

I have an amplifier that went bad on the left channel a couple of days ago. I'm kinda intrigued by the failure and symptoms, which is also why I'm posting here and not just counting my losses. I was ...
0
votes
1answer
63 views

Simple method to find open fault in three wire power cable?

I have a three wire power cable - live, neutral and ground. My multimeter shows no fault with the neutral and ground wires, but there is an open fault on the live wire. Nothing suspicious upon visual ...
1
vote
1answer
121 views

What's the use of the ground socket of an ungrounded GFCI receptacle?

Is the ground socket of a GFCI receptacle that isn’t connected to ground useful? (I'm in the United States, if it matters.) If the connected appliance had current on its ground pin, where would this ...
-3
votes
2answers
213 views

Setup for logging/displaying what command an OBD scan tool sends

I came across this video: youtube.com/watch?v=VtMvccqE8ks Any idea/resources how to build this setup? I am not much interested in monitoring the CAN bus for commands (headers or CAN IDs) of power ...
0
votes
1answer
84 views

Fault finding (Basic) [closed]

I am currently trying to work out whether a particular PCB is faulty. The board consists of a low capacitance a.c filter in parallel across the line and neutral. The circuit also consists of ...
5
votes
1answer
132 views

Diode stops conducting. Conducts again after applying higher voltage. What happened there?

I have the following circuit for providing regulated 5V from a 12V power supply: I have several hundreds of PCB with this circuit, and they work fine. However recently I have had a few of these PCBs ...
0
votes
0answers
94 views

The effect of series & parallel resistors/impedances on fault level

Can anyone explain or link to a source that explains this? Simply put, what is the effect of having resistors/impedances in series/parallel on the fault level of a circuit? I haven't been able to ...
2
votes
1answer
77 views

What types of fault protection is recommended for low voltage power supplies?

I'm building an AC-DC 120/15 V isolated power supply using a transformer, buck regulator for constant voltage, and a diode bridge rectifier. I'm not sure what type of fault protection to implement, ...
2
votes
3answers
2k views

Amplifier Repair - How can I find a replacement transformer? [closed]

So I'm trying to repair an old Marantz 1040M amplifier, which after being run at high volumes on New Year's(!!) no longer powers on :( My electronics knowledge is fairly rudimentary, but I think I ...
0
votes
0answers
1k views

How to test darlington transistor in-circuit?

I'm trying to diagnose a faulty current limiting circuit in a piece of lab equipment from back in the 80s. The fault is too much current. The tail end of the circuit is below. Q3 represents a ...
-1
votes
1answer
380 views

STM32F4 bugs in DMA, is there bug-free version?

Producer has confirmed that if there will be concurrent AHB and APB2 transfers using DMA2, then data corruption will occur (source). The bug discovery is from 2012, many years ago. Is the STM32F4 ...
1
vote
3answers
360 views

Power System Faults Problem

A sustained three-phase fault occurs in the power system shown in the figure (See Link). The current and voltage phasors during the fault (on a common reference), after the natural transients have ...
0
votes
1answer
379 views

Three phase short circuit and line to ground short circuit

Why is three phase short circuit calculated current higher than line to ground or (phase to ground) short circuit calculated current in most cases?
0
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2answers
50 views

Bad Headphone Connector Wiring Issues - What Could Be Wrong? [duplicate]

I am trying to repair a headphone cable with a splice. The audio sounds really bad after the repair. I can hear instruments, but not the vocals. Also, the playback is mono, same sound on both sides. ...
0
votes
1answer
58 views

Repeated dimmer switch fault following bulbs reaching end-of-life

I have a dual 1-way dimmer switch, 240V rated for 40W-400W, to which one of the dimmers has 5 x 60W dimmable bulbs (ceiling lights) and always works without any issue, and the other dimmer has 4 x 28W ...
31
votes
6answers
4k views

How did smacking electron tube TVs help?

In old movies (or new movies playing in these times), I often see people smacking the top of electron tube TVs or screens. Somehow it seems to help to stabilize/sharpen the picture. But why? Are ...
1
vote
2answers
510 views

What is the difference between capacitive fault currents and resistive fault currents?

http://uk.megger.com/battery-ground-fault-tracer-bgft\ This website claims that it's product can differentiate between these two fault currents. But I don't know what the difference is.