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Isolation Transformer

Transformers with primary (input) and secondary (output) windings separated from each other are known as isolation transformers. Under this construction, the input power and the output power are electrically separated by an dielectric insulation barrier.


Isolation Transformer Winding Diagram

Isolation Transformer



Advantages of using an isolation transformer

  • The primary and secondary winding can be constructed as a step-up or step-down transformer to match the load in the electrical system
  • Preventing the equipment from getting spikes and harmonics from the mains
  • Safety. There will be no conductive connection between the live part of the circuit and earth. With the isolating transformer, there is no danger in touching the live while the body is earthed.
  • By connecting the electrical system safety ground to the neutral conductor on the transformer secondary, it eliminates neutral-to-ground voltage and noise. This resolves reliability problems for microprocessor-based electronics.

Isolating transformers are also the most common kind of transformers for voltage step-up and step-down usage.However, 1:1 ratio transformers, where input and output voltage are the same, are also widely used to solely take advantage of the isolation.


Step-down Autotransformer

Step-up Autotransformer
Step-down Autotransformer Step-up Autotransformer


In an autotransformer, the primary and secondary share a common winding. The secondary voltage always has a common terminal with the primary. Step up or down of the voltage is achieved by a tap from the winding measuring from the common end. For example, a secondary tap at 50% of the winding will produce a voltage half of the input.

Advantages of using an Autotransformer

  • Lighter in weight and smaller in physical size as it requires fewer windings and a smaller core.
  • Less costly compared to an isolation transformer.
  • The advantages listed typically are for autotransformer with voltage ratio ranging up to 3:1 voltage or vice versa. Beyond this range, an isolation transformer is usually more economical.


  • There is no isolation between the primary winding and the secondary winding. Therefore protection of the equipment is dependant on the supply devices.
  • As the primary and secondary share a common end, if the neutral side of the primary voltage is not grounded, the secondary side will not be either.
  • A failure of the winding insulation of the autotransformer will result in full input voltage applied to the output.
Posted in Hold-Tite Fasteners Hand Dryer - FAQs By Ballast & Transformer Team

Types of Screw Points

2014-05-03 9:06:00 PM

Product Selection

  • Die point

    Die point

    One of the least expensive pointing operations applied at the time of heading. This operation provides an end chamfer starting with a diameter smaller than the root diameter of the thread. The minimum reduction of the point is approximately 10% below the maximum minor diameter with an included angle of 40 to 50.

  • Dog point

    Dog point

    A straight pointed section reduced in diameter slightly below the root diameter of the thread. Usually extending In length about two-thirds the diameter of the thread. Recommended for ease In starting, to insure against stripping fine threaded products, and to increase efficiency along production lines.

  • Rolled point

    Rolled point

    An efficient method of producing pointed long studs or long screws with an end chamfer similar to the Die Point. The last thread and a half is slightly cupped by the thread roll-over operation.

  • Pinch point (rounded)

    Pinch point (rounded)

    An Inexpensive method of applying a 40',60' or go' lead-in point having a slightly rounded contour but with pinch-off marks on Its surface. Used for aligning several. sheets or assembling several parts requiring pilot action.

  • Nail point (pinched)

    Nail point (pinched)

    Usually supplied with an approximate 45' Included angle having a sharp point and slightly squared surface. Used for Impinging or locking against wood or other solt material. Other degrees of Included angle and sharpness also available.

  • Cupped point

    Cupped point

    A special cup section supplied on the end of the threaded member having a depression In the end to reduce the area In contact with the surface which increases Its holding and locking power under pressure.

  • Round point

    Round point

    A dome-like rounded surface applied to the end of a threaded member In order to offer pressure without disfigurement. Used for adjusting, members where friction without cutting action Is desirable.

  • Cone point

    Cone point

    A precision forming operation to provide any required Included angle. Offers a smooth surface, accurate length, and a sharp point which can be produced to any desired contour to fit your particular requirements.

  • Type A point

    Type A point

    A thread forming screw for use in thin metal .015 to .050 thick. Used with drilled, punched or nested holes in sheet metal, resin impregnated plywood, asbestos combinations, among others. Not recommended for new design.

  • Type B point

    Type B point

    A thread forming screw for use In heavier metal .050 to .200 thick. Larger root diameter with finer thread pitch for light and heavy sheet metal non-ferrous castings, plastics, Impregnated plywood, asbestos combinations, and other materials.

  • Type AB point

    Type AB point

    A thread forming screw combining locating type point of Type A with thread size and pitch of Type B. Normal limitations of Type B apply.

  • Type C point

    Type C point

    A thread forming screw with either coarse or fine pitch machine screw thread and blunt tapered point. Eliminates chips and permits replacement with standard screw In the field. Higher driving torque required. Usable In heavy sheet metal and die castings.

  • Type U point

    Type U point

    A thread forming screw with high Helix thread for driving or hammering into sheet metal, castings, fiber or plastics for permanent, quick assemblies.

  • Type F point

    Type F point

    A thread cutting screw with machine screw thread with blunt tapered point. having multi-cutting edges and chip cavities. For heavy gauge sheet metal. aluminum, zinc and lead die castings, cast Iron, brass and plastic.

  • Type FZ point

    Type FZ point

    A thread cutting screw with a tapping screw thread with blunt tapered point and multi-cutting edges and chip cavities. For plastics, die castings, metal clad and resin impregnated plywood, and asbestos.

  • Type 1 point

    Type 1 point

    A thread cutting screw with single flute for general use. Produces a fine standard machine screw thread for field replacement.

  • Type 17 point

    Type 17 point

    A thread cutting screw for wood with a coarse tapping screw thread and a special long sharp point fluted to capture chips.

  • Type 23 point

    Type 23 point

    A thread cutting screw in the fine thread series offering maximum thread cutting area and excellent chip clearing, with minimum tightening torques.

  • Type 25 point

    Type 25 point

    A thread cutting screw similar to Type 23 point except with coarse Type B thread. For plastics and other soft materials with large chip clearing and cutting edges.

  • Self-drilling


    With special drilling points-lengths-diameters that will drill through '1/4" metal. Eliminates all hole preparation-drills faster than a drill. No punching: drilling or tapping required. Reduces die costs.

  • Self-drilling


    Produces more secure sheet metal assemblies faster...used as self-drilling screw or driving thru pre-punched holes. Can be used with or without' pilot holes. Positive rake "forward cutting edge" drills straight thru sheet metal at peak speed. Perfectly mated threads Increase strip and back out pressures.

Posted in Hold-Tite Fasteners By Tom

How To Measure

The length of the screw and bolts is measured from the largest diameter of the bearing surface to the extreme point.


Posted in Hold-Tite Fasteners By Tom
3 Item(s)