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A transformer is a static electrical device that transfers electrical energy between two or more circuits. A varying current in one coil of the transformer produces a varying magnetic flux, which, in turn, induces a varying electromotive force across a second coil wound around the same core.
Electrical energy can be transferred between the two coils, without a metallic connection between the two circuits. Faraday's law of induction discovered in 1831 described the induced voltage effect in any coil due to changing magnetic flux encircled by the coil.
Transformers are used for increasing or decreasing the alternating voltages in electric power applications, and for coupling the stages of signal processing circuits.
Since the invention of the first constant-potential transformer in 1885, transformers have become essential for the transmission, distribution, and utilization of alternating current electric power. A wide range of transformer designs is encountered in electronic and electric power applications. Transformers range in size from RF transformers less than a cubic centimeter in volume, to units weighing hundreds of tons used to interconnect the power grid.

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  1. J

    Switch before or after transformer?

    Hello- I'm planning to install a bunch of LED lights in my kitchen cabinets. The idea is to have a small LED strip turn on automatically when opening the cabinet door. I've found a 12v LED strip that can be cut into 30cm long sections that will be perfect for my application, along with some...
  2. S

    Hazardous areas - control voltage transformer earthing -

    I've been in an ongoing debate regarding earthing of a control transformer and i'd like some other opinions. 690 primary, 120v secondary supplying control circuits (contactors/DC convertors etc), the neutral is tied to earth - My issue is the location that it is tied to Earth. As far as I know...
  3. captaincaveman

    Do MR16 Led bulbs require a LED driver or a transformer?

    Hi guys, Quick question regarding 5x MR16 (Gu5.3) Led bulbs in downlighters. The customer used to use halogen but has moved over to LED. They had stopped working due to a faulty 12v transformer I've just replaced the transformer with a constant voltage driver (1-25w) but with any more than 3...
  4. L

    Domestic Please the end of my tether with transformer/Ring

    Hi guys, Really hoping for some simple advice after a 2 year battle with my Ring Pro doorbell. To cut a long story short, and spending £ on several plugin transformers and multiple replacement Pros, I have decided to use the 24v bell transformer supplied from Ring. So, (and excuse incorrect...
  5. S

    Trainee LED transformer advice needed

    Hi, I’m wanting to remove two plug sockets that are labelled 12v only linking two strings of led 15mm spot lights. I would like to replace them with in line transformers and hide under the fireproof downlight covers in the loft. One plug is 6v 500mA DC leading to bathroom led lights x6 (2watt...
  6. N

    Domestic CAn I wire 12v downlighter transformer into dimmer circuit?

    Hi all. I've bought couple of LED tape kits which come with a 3pin 12v transformer. one of them is now wired into a simple circuit which is a single on/off switch and works great. the second set is to go into another room, again single switch but this time it's a dimmer not toggle. The kit is...
  7. C

    Transformer Neutral Grounding

    Should the neutral of the transformer be provided with separate ground rod or can it be interconnected with earth bar which also connects the transformer frame and other equipment frame grounding. Is it correct as per the European standards? ( See the attachment)
  8. spamwize2

    IR testing through transformer

    Hi all need some help, I've got a panel to test 400vac to transformer but after step down 110vac, do i megger it all at 1000v or just ignore transformer and megger at 250vac?
  9. E

    Wattage or Amperage of Transformer

    I have seen a transformer rated at 10,000 watts with input voltage of 110v and output voltage of 220v. Can input voltage of 110v and wattage of 100 watts produce the output of 10,000 watts? What determines the amperage or wattage output of a transformer? The voltage input/output formula is...
  10. M

    Increasing supply, does DNO transformer look excessive?

    Basically customer currently only has a 100A 3 phase supply, which is rather overloaded. Also has a 120KVA generator for a 55KW motor. Im trying to get a larger supply so everything will run off the grid and not overloaded. Ive spoken to the DNO in terms of trying to get a 400A supply. DNO...
  11. D

    Industrial Inspections and testing HV/LV transformer.

    Does anyone can recommend company or person from East Sussex which can do inspection and testing for transformer HV/LV ?
  12. W

    will LED's work with this transformer?

    Hi, I need to replace some kitchen lights that take G4 pin bulbs. I'd like to switch to LEDs but not sure if the transformer fitted will be too much power? Please see image and these are the bulbs I'm looking at: WOW - G4 LED 3W Bulbs Capsule Bulb Replace Halogen Bulb AC / DC 12V 48 3014 SMD |...
  13. S

    Christmas lights transformer rating

    Hi I’ve got a set of filament lamp Christmas lights, which I think is quite old. It is a set of 80 lights, and the lamps are rated at 2.4V, 0.29W, 120mA. The transformer is rated 24V(AC), 0.7A, 16.8VA. It had 8 ballast lamps installed, so I assume 1 ballast lamp for a string of 9 normal...
  14. A

    Transformer to out put 27 volts

    Hi, I have 6 x 4.5 volts led lights. Each has a 3 x 1.5volt AAA battery. Total 27 volts. I want to use a transformer to connect the six lights instead of using batteries. Please advise me on what type of transformer and where to buy it from. Thank you.
  15. R

    110 v site transformer repair ?

    I was given a couple of 3 kva site transformers, both have broken bases and all the sand has leaked out, epoxying a new base on is no problem, and I will only be using them myself at home, but what kind of sand should I refill them with ?
  16. S

    Lighting Transformer - requires earthing?

    Hi E.F. I am replacing 3 lighting transformers in my kitchen. The existing ones plug into 3 x main sockets which are on the AC mains circuit via a light switch and are earthed. The replacement transformers have no earth connection - do I need to earth the new transformers? If so, how? It's a DIY...
  17. L

    Va on a transfomer for watts

    I wanted to get one of these transfomers: What does the 100va mean, how many watts can I put through this is I run from 240v mains, from the 12v side? Thank you :-) Leo
  18. S

    Does this bell transformer have overload protection?

    Hi Folks I bought one of these Door Bell Transformer | Stevenson Plumbing & Electrical Supplies - as it's SELV and supports illuminated pushes, but can't find any...
  19. E

    Skinflint Seeks Free Advice on burnt-out LED Transformer

    Morning. The LED light above my bath doesn't work. I yanked all the stuff out the ceiling and found this. So far, so good. But hark! I have come to the conclusion that something is wrong with the transformer. Worst case: it may never transform again. If I just buy another one with the...
  20. the pict

    Welder transformer zapped

    Hi all I need a bit of help from the wise wizards I mate has a heavy duty mig welder which gave up the ghost on him I have had it apart the transformer that supplies 24vDC has no continuity through the primary and on close inspection the "in" if you like has detached itself from the terminal...