Questions tagged [fault]
83
questions
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1answer
44 views
Power system fault analysis
I have been stuck in this problem for identify the fault location. Can anyone show me where to start on this? I'm not familiar with reading the curves so please just give me any hint.
Thank you
3
votes
1answer
98 views
Difference in current transformers conection for ground fault detection
I have seen that for detecting ground faults on a 3-phase system powered by a secondary wye connected transformer, current transformers (CTs) can be connected in several ways:
On the ground ...
0
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0answers
34 views
short circuit fault power-flow
Can anyone explain to me, how to write a MATLAB code to solve for Newton-Raphson power-flow during a short-circuit fault?
Like, as far as I know, I need to change the Y-bus matrix (remove the row &...
0
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3answers
71 views
Line to ground faults
I am having a trouble understanding the concept of line to ground faults,and ground in general.
In this simple single phase circuit, does current reach the load and the circuit operates normally? ...
1
vote
3answers
270 views
STM32F4 HardFault_Handler
I've been trying to program an STM32F412RG but my program is stucked at HardFault_Handler once debug starts.
My board is an Wio LTE EU Version and I'm trying to ...
1
vote
1answer
62 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
65 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
votes
1answer
36 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
59 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
62 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
votes
2answers
120 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
65 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
172 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
88 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
votes
1answer
77 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
188 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
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1answer
41 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
vote
2answers
141 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
vote
3answers
158 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
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1answer
42 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
32 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
77 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 ...
2
votes
1answer
419 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
476 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 ...
0
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2answers
396 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
108 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
votes
2answers
654 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
267 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
111 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
66 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....
4
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
107 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
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0answers
475 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 ...
0
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2answers
2k 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
727 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
65 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
135 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
216 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
88 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
137 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 ...
2
votes
1answer
86 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 ...
-1
votes
1answer
444 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
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3answers
397 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
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1answer
413 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
61 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 ...
