Toroidal Transformers

Standard Toroidal Isolation Transformers | Toroidal Transformer Construction | Medical Grade Isolation Transformers | Low Profile PC Mount Toroid Transformers  | Features Of Toroidal Transformers | Low Profile Miniature 50/60Hztransformers | Toroidal Power Inductors   |  Current Transformers | Standard Toroidal Auto Transformers | Why Choose A Toroidal Transformer

About Toroidal Transformers These are power transformers utilizing a toroidal core. Primary and secondary coils are wound on this core and the toroidal shape allows for a shorter mean length per turn, reducing I2R losses in winding which are the main losses in this type of transformer yielding a smaller design improving overall efficiency. Toroidal Transformer Construction Line frequency toroidal transformers start with a core made from a continuous strip of thin, typically M4, grain-oriented electrical grade silicon steel. Silicon grains in the steel are oriented based on the rolling direction of the steel and is slit parallel to that orientation, creating the preferred path for magnetic flux. Strips are available in numerous widths; for smaller and mid-sized cores these are typically available in 1mm increments, and larger toroidal cores strips are available in 5mm increments.This steel has a thin inorganic coating for high interlaminar resistance, providing insulation between lamination windings and a good stacking factor. To create the core, a strip of grain-oriented electrical grade silicon steel is tightly wound under controlled conditions and tension on a mandrel, similar to a clock spring with the ends spot-welded in place, assuring a firm and congruous magnetic path. Unfortunately winding of the core creates mechanical and magnetic stresses, which change the molecular structure of the core. To return the material to a fully stress relief condition, the core is placed in an annealing furnace. Using a precise heating and cooling profile ensures that the silicon grains are in the single preferred magnetic direction.   Core insulation consists of four layers of 2mil polyester film (other materials are available) applied to the core using a toroidal tape winding machine. This insulation provides 100% surface coverage, also protecting and cushioning the core from the windings and reducing vibration. Primary windings are applied by a toroidal winder and if needed lead wires are attached. The primary to secondary insulation uses the same process and materials as the core insulation, to meet standard test requirement of 4kV RMS for 1 minute between primary and secondary. Secondary windings are applied by a toroidal winder and if needed lead wires are attached. The copper wire has a base coat of polyester and heavy topcoat of an amide imide (200°C). The copper wire is wound uniformly over the entire core to provide: better heat dissipation, minimum flux leakage, and to maintain a low voltage between adjacent turns. The outer insulation is then applied using the same process and materials as the other insulation layers, except only two layers of polyester film are used. Toroidal Transformer Design Options Thermal Protection - Usually in primary circuit, normally closed-auto reset opens at high temperature UL, CSA, VDE listed components. Center Hole Potting - Thermoplastic material for high mounting precision. Threaded insert or press fitted stud is optional. Thermally conductive compound is available. Electrostatic Screen - Copper foil (2mil) laminated between polyester film and tape to reduce capacitive coupling between primary and secondary windings, tightly wound over primary insulation. Medical / Safety Shield - Polyester laminated (5mil) copper foil creates a physical barrier between primary and secondary windings, terminated at one end with green and yellow earth wire to meet UL2601 and IEC601. Magnetic Shield - Several turns of silicon grain-oriented silicon steel are tightly wound around the toroidal circumference, fixed in place by outer insulation. Toroid Mounting Options     Toroid Mounting - Disk       |       Toroid Mounting - Flange        |    Toroid Mounting - PCB Toroid Metal Disk Mounting Exploded View Why choose a toroidal transformer for your line frequency applications? 50/60Hz power toroidal transformers have unmatched flexibility and efficiency providing a higher performance compact transformer. Since there is no air gap, it results in a stacking factor of 97.5% of its weight. Power toroidal transformers can also operate at higher flux densities than E-I transformers, thus reducing the number of turns necessary to induce a given voltage across the same cross section of the core. This means a lower series resistance in the winding, reducing the I2R copper losses. Given the same power output requirements, ambient temperature, and temperature rise allowances, a toroidal transformer will use less material to produce an equivalent transformer leading to a smaller and lighter solution than an equivalent E-I laminated transformer. With all the above reasons the question should not be “Why choose a toroidal transformer,” it should be why not! Toroidal Transformer Core Compared to EI Core Features of Toroidal Transformers   SIMPLIFIED MOUNTING A one bolt mounting scheme easily and quickly mounts the toroid, avoiding costly mechanical design and tooling charges associated with the first piece of custom conventional E-I laminated transformers. A power toroid, toroidal auto transformers and toroidal medical grade isolation transformers have a low center-of-gravity along with reduced weight, such that a lower gauge sheet metal is required to support a toroidal transformer. This, further reduces your product’s weight and material and labor cost by eliminating three screws per assembly.   LOW NO-LOAD LOSSES Compared to conventional E-I transformers, toroidal power transformers have extremely low no-load losses. When used in an application where a circuit is in a quiescent or “stand-by” mode for long periods of time, the potential power reduction can be significant, sometimes 80% to 90% lower.       LOW WEIGHT Because they are more efficient, toroid isolation transformers and toroidal auto transformers can be up to 50% lighter (depending on power rating) than E-I laminated transformers. Low weight simplifies end product design by reducing mounting hardware and supporting enclosure requirements.       LOW ACOUSTICAL NOISE The core of a toroid transformer is formed from a single strip of grain-oriented electrical grade silicon steel, tightly wound in the form of a clock spring with the ends spot-welded in place. The copper wire is wound over polyester film, forming a silent, stable design without the use of environmentally harmful glues or varnishes. It will not clack or buzz anywhere near the level as would many pieces of separate lamination under the same changing magnetic field. The core actually intensifies the field, not contributing to the problem of layer-to-layer vibration.   HIGHER EFFICIENCY The combination of very low core losses (1/2 watt per pound), a lower mean length per turn, and fewer turns yield lower I2R losses. This unique construction allows toroid power transformers to be typically between 15% and 30% more efficient than E-I laminated transformers. As a rule, the larger the transformer the more efficient a toroidal transformer becomes.       LOWER OPERATING TEMPERATURE Since most of the losses in a toroid transformer are in the copper wire, the toroid cools off quicker than the conventional E-I transformer type with more iron. At half the load, the toroidal transformer's temperature rise is only about 30% of what it is at full load.     FLEXIBLE DIMENSIONS Power toroids and power chokes are not constrained to specific lamination sizes. Since the height and diameter of toroids may be carefully varied, it allows flexibility to accommodate specific height and width design requirements. RADIATE LOWER MAGNETIC FIELDS Toroid transformers, including toroidal medical isolation transformers, are made from one solid piece of material focusing the field within the core. In addition, the primaries and secondaries are wound uniformly around the entire core. This results in very low radiated magnetic fields. The toroidal transformer is perfect for applications with circuitry, which is highly sensitive to stray magnetic fields. In certain cases, the single bolt mounting allows the toroid to be rotated in place, to yield the best possible results without any additional tooling or sheet metal work. This can be specifically important in medical equipment having especially sensitive electronics; a toroidal medical isolation transformer typically can be placed in closer proximity to these electronics without additional shielding. SMALL SIZE Toroidal power transformers have lower core loss, operate at a higher flux density, and allow the conductive windings to be in intimate contact with the core. This enhances current flow at all points in the core yielding a transformer, which is smaller than its E-I transformer counterpart. Electrical and mechanical designers appreciate a toroid’s compact dimensions especially where low height is a consideration.   Standard Toroidal Isolation Transformers   These standard toroidal transformers provide general isolation for general purpose applications for most electrical products which require a step-down or step-up in voltage. They consist of dual 117 V primaries and dual secondaries. Power capacity ranges from 100 to 3,000 VA.   By offering dual primaries these are easily configurated for 120 V or 240 V operation. Dual secondaries range from 2 to 12 V windings to 2 to 120 V windings. This variety offers the option of stepping down/stepping up your linevoltage or simply providing isolation from your voltage source to your equipment.   Toroidal Isolation Transformer Schematic     Standard Power Toroidal Transformers Include: Dual 117 V primaries for 120 V or 240 V operation Secondary voltage options 4 kV isolation between primary and secondary windings Standard mounting options 10″stranded leads Standard Power Toroidal Transformers Part Number VA Rating Secondary Voltage OD Height Weight Secondary Current   Competitor P/N Reference XF-00100-2012 100 2 x 12 3.8" 1.8" 2.4 2 x 4.16  AA50952-012 XF-00100-2015 100 2 x 15 3.8" 1.8" 2.4 2 x 3.33  AA50952-015 XF-00100-2018 100 2 x 18 3.8" 1.8" 2.4 2 x 2.77 AA50952-018 XF-00100-2024 100 2 x 24 3.8" 1.8" 2.4 2 x 2.08 AA50952-024 XF-00100-2030 100 2 x 30 3.8" 1.8" 2.4 2 x 1.66 AA50952-030 XF-00160-2012 160 2 x 12 4.0" 2.2" 3.6 2 x 6.66 AA51852-012 XF-00160-2015 160 2 x 15 4.0" 2.2" 3.6 2 x 5.33 AA51852-015 XF-00160-2018 160 2 x 18 4.0" 2.2" 3.6 2 x 4.44 AA51852-018 XF-00160-2024 160 2 x 24 4.0" 2.2" 3.6 2 x 3.33 AA51852-024 XF-00160-2030 160 2 x 30 4.0" 2.2" 3.6 2 x 2.66 AA51852-030 XF-00160-2120 160 2 x 120 4.0" 2.2" 3.6 2 x 0.66 AA51852-117  XF-00225-2012 225 2 x 12 4.6" 2.2" 5.1 2 x 9.27 N/A XF-00225-2015 225 2 x 15 4.6" 2.2" 5.1 2 x 7.5 AA52402-015 XF-00225-2018 225 2 x 18 4.6" 2.2" 5.1 2 x 6.25 AA52402-018 XF-00225-2024 225 2 x 24 4.6" 2.2" 5.1 2 x 4.68 AA52402-024 XF-00225-2030 225 2 x 30 4.6" 2.2" 5.1 2 x 3.75 AA52402-030 XF-00225-2120 225 2 x 120 4.6" 2.2" 5.1 2 x 0.93 AA52402-117 XF-00300-2015 300 2 x 15 4.6" 2.9" 6.5 2 x 10 AA53002-015 XF-00300-2018 300 2 x 18 4.6" 2.9" 6.5 2 x 8.33 AA53002-018 XF-00300-2024 300 2 x 24 4.6" 2.9" 6.5 2 x 6.25 AA53002-024 XF-00300-2030 300 2 x 30 4.6" 2.9" 6.5 2 x 5 AA53002-030 XF-00300-2042 300 2 x 42 4.6" 2.9" 6.5 2 x 3.65 N/A XF-00300-2120 300 2 x 120 4.6" 2.9" 6.5 2 x 1.25 AA53002-117  XF-00400-2024 400 2 x 24 5.4" 2.4" 7.2 2 x 8.33 AA53752-024 XF-00400-2030 400 2 x 30 5.4" 2.4" 7.2 2 x 6.66 AA53752-030 XF-00400-2042 400 2 x 42 5.4" 2.4" 7.2 2 x 4.76 N/A XF-00400-2055 400 2 x 55 5.4" 2.4" 7.2 2 x 3.63 N/A XF-00400-2120 400 2 x 120 5.4" 2.4" 7.2 2 x 1.66 AA53752-117 XF-00500-2024 500 2 x 24 5.4" 2.8" 8.8 2 x 10.41 AA54602-024 XF-00500-2030 500 2 x 30 5.4" 2.8" 8.8 2 x 8.33 AA54602-030 XF-00500-2042 500 2 x 42 5.4" 2.8" 8.8 2 x 5.95 N/A XF-00500-2055 500 2 x 55 5.4" 2.8" 8.8 2 x 4.54 N/A XF-00500-2120 500 2 x 120 5.4" 2.8" 8.8 2 x 2.08 AA54602-117 XF-00650-2024 650 2 x 24 6.0" 2.9" 11.5 2 x 13.54 AA56252-024 XF-00650-2030 650 2 x 30 6.0" 2.9" 11.5 2 x 10.83 AA56252-030 XF-00650-2042 650 2 x 42 6.0" 2.9" 11.5 2 x 7.73 N/A XF-00650-2055 650 2 x 55 6.0" 2.9" 11.5 2 x 5.9 N/A XF-00650-2120 650 2 x 120 6.0" 2.9" 11.5 2 x 2.7 AA56252-117 XF-00800-2024 800 2 x 24 6.4" 2.8" 13 2 x 16.66 AA58002-024 XF-00800-2030 800 2 x 30 6.4" 2.8" 13 2 x 13.33 AA58002-030 XF-00800-2042 800 2 x 42 6.4" 2.8" 13 2 x 9.52 N/A XF-00800-2055 800 2 x 55 6.4" 2.8" 13 2 x 7.27 N/A XF-00800-2120 800 2 x 120 6.4" 2.8" 13 2 x 3.33 AA58002-117 XF-01000-2030 1000 2 x 30 6.6" 3.3" 15.6 2 x 16.66 N/A XF-01000-2042 1000 2 x 42 6.6" 3.3" 15.6 2 x 11.9 N/A XF-01000-2055 1000 2 x 55 6.6" 3.3" 15.6 2 x 9.09 AA59902-055 XF-01000-2120 1000 2 x 120 6.6" 3.3" 15.6 2 x 4.16 AA59902-117 XF-01500-2042 1500 2 x 42 8.2" 3.0" 23.6 2 x 17.85   XF-01500-2055 1500 2 x 55 8.2" 3.0" 23.6 2 x 13.63   XF-01500-2120 1500 2 x 120 8.2" 3.0" 23.6 2 x 6.25   XF-02000-2042 2000 2 x 42 8.2" 4.0" 29 2 x 23.8   XF-02000-2055 2000 2 x 55 8.2" 4.0" 29 2 x 18.18   XF-02000-2120 2000 2 x 120 8.2" 4.0" 29 2 x 8.33   XF-03000-2055 3000 2 x 55 9.2" 4.1" 39 2 x 27.27   XF-03000-2120 3000 2 x 120 9.2" 4.1" 39 2 x 12.5

Standard Toroidal Auto Transformers

These standard toroidal auto transformers step-up or step-down line voltage, to suit your equipment’s input voltage requirement. Auto transformers consist of a single winding with various taps. They provide no isolation since there is no physical separation between the primary and secondary winding.

In circumstances where voltage isolation between the input and output is not needed, auto transformers are ideal. Since the primary and secondary windings of an auto transformer share common turns, you can expect a size and weight reduction of about 30-70%, which results in a significant cost reduction.

Toroidal Auto
Transformer Schematic

Our Standard Toroidal Auto Transformers Include:

• 115 V or 230 V input and a 115 V or 230 V output
• Power ratings ranging from 100 to 1,000 VA
• Standard mounting options
• 10″stranded leads

Standard Toroidal Auto Transformers

Medical Grade High Isolation Transformers

These medical grade high isolation toroidal transformers are integrated into medical devices used in hospitals, medical research facilities, and biomedical companies. They assist in bringing these electronic devices into compliance with the UL 60601 medical safety standard for an additional level of safety and protection.

Design, testing, and construction of toroidal medical isolation transformers are strictly monitored under safety regulations, guidelines and governing laws:

• Minimum air clearance
• Maximum patient leakage current
• Minimum creepage distance
• Maximum enclosure leakage current
• The values of test voltage (high potential voltage test between windings)
• Maximum patient auxiliary current
• Limited max. earth leakage current
• Maximum temperature rise at load and at over load

Standard Medical Isolation Transformers

Custom Toroidal Medical Transformer Designs

We can also provide custom medical isolations transformer designs to fit your specific needs. The popular configurations have a combination of the following:

• Custom primary and secondary voltage
• Variety of connection and harnessing options
• Custom mounting and enclosures to meet customer requirements
• Low height/easily configured into minimal space
• Custom medical transformer designs can be added to our UL medical file for a nominal charge

Low Profile Miniature Toroidal Isolation Transformers

Our low-profile miniature toroid isolation transformers are rated for 50/60Hz operation and have capacities up to 50 VA. Toroidal power transformers are mainly used in 115/230 V (50/60Hz) applications. They are easily mounted by using a single M4 bolt inserted in a through hole provided in the center of the potting. This provides secure and reliable means of mounting.

These toroidal power transformers are built to UL class A insulation system and are UL recognized to UL 5085-1 and UL 5085.

They’re also C-UL recognized to CSA C22.2 no. 66 and construction meets the requirements of UL 1950 VDE 0805 IEC 950 and EN60950.

Toroid Isolation Transformers offer:

• Greater efficiency
• Lower audible vibration
• Easier mounting
• Lower stray losses (leakage flux)

Toroidal Isolation Transformer Schematic
Low Profile Miniature Isolation Transformers

Standard Low Profile Miniature Toroidal Isolation Transformers

Low Profile PC Mount Toroidal Isolation Transformers

Our Low Profile PCB Mount toroidal power transformers come fully encapsulated in a plastic case. These are designed for through-hole PCB mounting, and are provided with a built-in central screw holder that will accommodate M4/M5 machine screws or self-tapping screws. This permits you to secure the toroidal Isolation transformer to the PC board prior to soldering.

There is also room inside the case allowing for other components to be included with the transformer to form a homogeneous unit. Typical components that can be added include: PTC thermistors, fuses, re-settable thermal switches, rectifiers and voltage regulators.

All low profile PC mount toroidal isolation transformer models are configured for 2x115 V Input voltages at 50/60Hz. They pass high voltage testing at 0.5 KVAC between primary to primary, secondary to secondary and 4 kV primary to secondary. They are specified at an ambient temperature of 70°F and can withstand elevated ambient temperatures of up to 70˚C.

Advantages of Low Profile PC Mount Toroidal Isolation Transformers:

• Low profile
• Low magnetic field radiation
• Acoustic noise virtually eliminated
• Compact size
• High efficiency
• Low leakage losses
• 4 kV isolation between primary and secondary windings
• Manufactured in an ISO 9001 approved facility
• Comply to UL 5085 and VDE 61558 (except for all 2 x 22 V models)
• Bear the CE mark
• Designed and built to meet Class F (155?C) insulation system requirements

Additional Features of Low Profile PC Mount Toroidal Isolation Transformers:

• 115 V or 230 V input and a 115 V or 230 V output
• Primary intended to be used in 115 V or 230 V @ 50/60Hz
• UL recognition for class A insulation
• UL recognized to UL 5085-1 and UL 5085-2
• C-UL recognized to CSA C22.2 no. 66
• Design construction meets UL 1950, VDE 0805, IEC 950
• Hipot testing between Primary to Secondary 4000 V (VDE0550)
• Maximum ambient temperature of +60°C

Standard Low Profile PC Mount Toroidal Isolation Transformers

Toroidal Power Inductors 50/60Hz

These standard power chokes come in ratings from 0.2Ws to 25Ws. Toroidal power chokes are most commonly used in line frequency (50/60Hz) AC circuits as part of a DC filter.

By using a toroidal power choke, you can reduce the physical size of the overall filter. This is through the size reduction yielded by the toroidal power inductor design and also the required filter capacitors in your LC circuit. The toroidal power inductor also contains any stray magnetic field, further enhancing your filter design.

Toroid Toroidal Power Inductors 50/60Hz offer:

• Greater efficiency
• Lower audible vibration
• Easier mounting
• Lower stray losses (leakage flux)

Standard Toroidal Power Inductors 50/60Hz