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Questions tagged [insulation]

An insulation or insulator, is a barrier of non-conductive material around electrical conductors and other circuit-components like resistors, capacitors, IC etc.

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Grounding a device with double insulation prohibited?

There are Class I and Class II electrical devices. Class I devices need to have live parts grounded and Class II have double insulation. Why grounding of class II devices is prohibited? I mean, we can ...
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84 views

Transformer Insulation - High Voltage can Jump Through Ferrite Core?

First of all, I really searched the topic on both EE.SE and Internet but could find nothing. If this is asked before, please forgive me. As I stated here earlier, I was working on an HV amplifier. ...
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High voltage dielectric breakdown & layering insulators

I’m going to use 230 kV as the reference voltage for the example below; I know if I put a piece of metal too close to a 230 kV source it will breakdown the air and jump to the piece of metal causing ...
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Proximity of Insulated Wire

I want to sell an electrical product with an earthed, metallic enclosure for commercial use in Europe. The wiring inside the product is pretty tight. Are there any laws that prevent me from having ...
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38 views

How to evaluate equivalent insulation resistance of two cables?

My guess was that the equivalent insulation resistance of two cables in parallel is same as the equivalent resistance of two resistances in parallel. But instead it is the sum of the two insulation ...
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34 views

What is the voltage between each turn in a transformer winding

From a perspective of insulation, how much voltage between each individual turn in a transformer? Example from picture above, the primary winding have 16 turns. Let`s say 800VDC is applied between + ...
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781 views

What is this translucent heat-resistant insulation?

On the picture from this question, what is the translucent insulation on the transformer center-tap made from? It looks like polyethylene, but it obviously isn't because PE would melt at soldering ...
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Coloured coating within CRT

I have noticed that a lot of CRTs have a coloured coating inside of them that would appear to have practical purpose other than maybe protecting the aquadag. Paints and plastics tend to be avoided in ...
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How to insulate a high voltage PCB trace?

I am making a PCB with a HV power supply module. Namely the C9619 module from Hamamatsu. The module produces up to 2 mA and 4 W of power so the heat won't be a problem The module can produce up to ...
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1answer
106 views

Name of fabric insulator found inside motors

What is the name of the fabric sleeve insulator used for components (typically fuses) and solder joints found inside motor windings? Can regular heat shrink tubing be used as a substitute? Image by ...
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How to solder Christmas lights insulated wire?

I want to fix Christmas lights like these, whose wires got cut near the batteries. The LEDs near the batteries still work. I tried touching the wires from the two parts and I was surprised that the ...
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Electrical isolation problems when routing between pads of SMT resistors/caps

According to answers to this previous question, routing traces between the pads of SMD caps/resistors, as shown in the picture, is not dangerous as long as trace to pad clearances are obeyed and the ...
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124 views

DC Motor Winding Insulation Material

As I understand it, the field coils and armature windings in a DC motor are insulated and this insulation can 'burn off' if the motor overheats, causing a short circuit to develop. What is the ...
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93 views

How are electric under blankets fail safe?

Electric under blankets are mains powered and yet you lie on them. 240V in the UK. They appear to effectively be a single resistive heating element. Clearly they're not earthed as that would be ...
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66 views

How to prevent noninsulated wires close together during manual wiring a PCB?

Actually I have two problems, but this one is most annoying: I have like 10 wires I want to solder to the pins of a pin header (2.54 mm distance apart). Initially I kept like 5 mm of the end of each ...
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104 views

Meggering Three Phase Motor (Phase-GND, Phase-Neutral, GND-Neutral)

When meggering a three phase motor, could someone please help me understand the values we would expect to see for a motor with no insulation or ground faults. From my understanding: Phase-GND: ...
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Are there disadvantages of heat shrink tubing with higher shrink ratios?

Heat shrink tubing comes in various shrink ratios. The most common of which is 2:1, but there are also 3:1, 4:1 and higher. Assuming cost is the same, are there any disadvantages or consideration ...
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84 views

Proper insulation of wires connecting to the submersible pump (5V)

I'm building a simple plant watering station, which uses a relay-controlled submersible water pump (this one). The intent is to submerge the pump into a large enough water container to avoid frequent ...
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151 views

How to strip pieces of insulation in a wire?

I would like to strip some insulation from a wire (like shown in the image below, the green area should be only the metal inside, no insulation). I was wondering how I could possibly do this. Cutting ...
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172 views

Insulation Voltage of Aluminum PCB - With and Without Electronic Components

We are working on a product that contains an LED module consists of 66 LEDs (33s x 2p - 100VDC load voltage). We'll use aluminum PCB due to the thermal requirements but the customer requirement ...
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1answer
81 views

Insulating from static electricity

I am happy to announce that my pocket extra-strong static electricity generator project is now complete and works well. However there is one problem, I am often getting zapped severely (to the extent ...
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1answer
64 views

the volt time constant of a pulse transformer

I am looking for a transformer to use with a RS485 driver, but I don't know on what criteria I am to pay more attention: Insulation Voltage or Volt-time constant. Can someone explain me if the volt-...
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1answer
50 views

Is thermally conductive epoxy needed if long settling time is acceptable?

I'm using SMD based analog temperature measuremet ICs (a version of the old TMP36). It will be mounted on a tiny and thin (.5mm) PCB I've cut to hold the IC and a few mfgr recommended parts and a 3 ...
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90 views

Material with fairly high resistivity, but allows flow of charge

Is there a material with fairly high resistivity (at least semi-conductor level), but also allows the flow of charge through it (and subsequently to the ground)? The flow of charge does not need to be ...
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172 views

What material(s) are used in IC's as insulating layers between metal layers?

This question and the answers hits close to the topic. One picture shows it as SOD. Silicon-oxide dielectric? I'm aware that around/within the transistor, silicon oxide is grown for insulation where ...
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2answers
939 views

How is clearance affected by altitude (air pressure)?

Let's say you have a high-voltage circuit (or any voltage really) and you want to provide appropriate clearance distance for the PCB, connector pins, etc. (Above image from link) There are standards ...
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1answer
89 views

Megohmmeter, Insulation tester, megger

Can anyone please explain how does megohmmeter (insulation tester) work. Here is what I don't I don't understand: These little tester can produce e.g. 1000V, how is that done? What are the internals ...
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611 views

How to safely insulate the Power PCB of a display computer monitor?

CONTEXT The other day I was checking the heat coming off an aluminium heatsink on the power PCB of an eizo EV line led display monitor. It was okay, not too hot, just warm and tad bit hot. When I ...
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1answer
91 views

Isolation for TO-247 Leads at High Voltage (1000V)

Regarding the fairly new High Voltage SiCFET Devices with operating voltages of 1200V+ in leaded TO-247 packages (or variants thereof): How to isolate the Gate-, Drain- and Source- leads (and ...
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2answers
61 views

Insulation resistance tester: orders of magnitude difference in measurement depending on connection polarity

https://youtu.be/eGjd7HoYyz8?t=115 The man on the video is measuring a transformer's insulation resistance, the resistance measurements are very different depending on how the meter is connected: ...
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72 views

Why insulation resistance goes linearly

While we test electrical equipment like transformer the insulation readings goes higher linearly over time,And even to infinity which means the instrument could not measure beyond that, 15Tohm is the ...
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1answer
97 views

Will copper wire with a non-tarnishing coating be insulated?

I need to make a coil to test voltage created by flux for a project, but bought the wrong grade of wire. Will the non-tarnishing coating act as a good enough insulator for voltages in the millivolts? ...
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83 views

change electric field orientation

Need to change the orientation of an electric field from one angle to another. Setup is similar to an ordinary capacitor. There’s an insulator material in the middle and two electrodes on both sides ...
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3answers
154 views

How does a cable insulator prevent energy loss?

So I was watching a recent video for TED-ED titled "How to practice effectively...for just about anything - Annie Bosler and Don Greene," and at one point the speaker said the following: Myelin is ...
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111 views

How is underground electrical infrastructure insulated

I know that overhead power lines use ceramic power-line "holders" to insulate the high voltage current from grounding itself from the poles. But how do underground power lines avoid grounding? What ...
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4answers
810 views

Can your teeth come to harm when using them to strip thin wire? [closed]

When my dad saw I was stripping the insulation off thin tinned copper wire using my teeth he said that this was dangerous because parts of my teeth could break off. I can't believe this because it's ...
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2answers
157 views

Function of earth screw terminals in power supplies with plastic cases

This is about use of earth screw terminals which are often provided in power supplies. Below is an Embedded Switch Mode Power Supply with a metallic case: Here I can understand how the earth wiring ...
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116 views

Insulating a thermistor

I have an NTC Temperature Sensor thermistor connected to a PID Temperature Controller. The main use of this controller is to control the temperature of chemicals in a reactor. Due to the environment ...
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162 views

How to tell the difference between heat shrink tape and normal wire tape?

Heat shrink tape Wire tape They look exactly the same, especially with the absence of any markings on the ring... How can I tell the difference between the two?
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1answer
153 views

Electrical Discharge Machining (EDM) an insulated metal

I am interested in using a Wire EDM process to cut some silicon steel. As defined by Wikipedia - “Electrical discharge machining (EDM), also known as spark machining, is a manufacturing process ...
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1answer
477 views

Should the thermocouple wires be insulated against a metal shaft

I am working on a project where I am using Omega bare TC. Its just two wires welded at the tip. I am using MAX6675 coupled with an Arduino. Should one of the two leads be insulated? The bare ...
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2answers
182 views

How can I get shocks while charging my phone in the train?

Ever since I got a phone with a metal chassis I get this issue : if my phone is plugged to a train electric outlet and I simultaneously touch my phone and any metallic part of the train (such as an ...
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2answers
267 views

Is it safe to touch a running 1 hp electric motor?

This question is about touching the housing of a generic AC electric motor like this one: ...while it's running, without considering any type of insulation, such as wooden floor, rubber gloves or ...
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4answers
325 views

Tiny shock from 230V AC?

So first at all this question isn't really about electrical engineering, but about electricity in general. However, I think this is the best place to ask, correct me if I’m wrong. Also I’d like to ...
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3answers
644 views

How low an insulation resistance is too low for a residential electrical system?

I have had occasion recently to test the wiring of a residential building for damage from a lightning strike. I opened all the breakers, removed all the loads, opened the panel, and meggered each hot ...
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75 views

Digital insulation meter measurement limits

A Meggar digital insulation meter user manual warns: "When using 500 V measurement to measure resistance less than 1.5 MΩ or 1000 V to measure resistance less than 5 MΩ, measurement time must not ...
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1answer
527 views

Insulate a copper wire in home condition

I know I could buy magnet wire but unfortunately, the availability of magnet wire in my area is close to non-existent. I'm looking to make 2 transformer coils one of 60 turns AWG10 (5 metre) and one ...
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1answer
190 views

Insulation Resistance Calculation

I am trying to calculate the minimum insulation resistance of two parts (a capacitor and box) that are approximately 0.38mm apart or 0.00038m. I've tried looking at resistivity of air which some ...
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142 views

Recommended isolation paper for hobby circuitry [closed]

I'm having a hard time finding out what type of insulation is enough for my projects. I will be building this: STM32 OLED Soldering Station Case Temperature Controller T12 KR BL ILS BC2 Handle ...
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182 views

How can I protect a picoammeter or a picoscope in HVDC measurements?

I'm trying to measure the leakage current along an insulator energize with HVDC (the effect of space charges is been considered). Can I connect a picoammeter to the ground electrode? If yes, please ...