| Description | This series of isolation transformers is optimized for medical equipment applications. Three types are offered, based on the 601 class of equipment and the specific requirements for electrical shock and thermal protection. As well as meeting stringent medical safety standards, this series addresses requirements for low RFI and EMI, all in the high power densities of toroidal construction. Available in 16 power levels from 100VA to 12500VA. |
Standards
 | Construction verified by Canadian Standards Association to: CE, EN-60065, VDE 750; UL 544, UL 2601; CSA 22.2 No. 601.1:1988; IEC 65, IEC 950, and IEC 1010-1:1990. CSA file No. LR-854566-9. Transformers are intended for use in end-product equipment where the suitability of the combination is to be determined by the appropriate approval authority. |
| Inputs | Dual 0-100-120 VAC windings, series or parallel connected for 100, 120, 200, 220 or 240VAC at 50 / 60 Hz. |
| Insulation | UL approved class F (155°C) system to CSA C22.2 No. 0-M91, appendix B. UL file No. E181839. Complies to standard UL 1446.
Class F insulation systems allow a maximum single fault temperature of 170°C, 190°C for abnormal overload tests.
Primary to secondary includes both basic and double reinforced insulation, per IEC medical publications, Section 57 (formerly Appendix J). Minimum creepage 8 mm and clearance 5 mm. Tested to 4 kV primary to secondary for minimum one minute. |
| Output Tolerance | Better than 3% at full load. |
| Mounting | All units in this series are supplied with a potted center and an integral neoprene washer base. The potting compound is UL-HB approved, or better. A single mounting hole with a recessed base is provided on units from 100VA to 3000VA. 4000VA to 12500VA transformers have a flat base with two mounting holes. See mechanical table for details. |
| Thermal Protection | Mains transformers used in medical applications require a protective device to ensure insulation does not overheat in the event of a short circuit. It is possible to either include one-shot thermal fuses or thermal switches into the transformer, or, protective devices can be external to the transformer.
Type 1 and 2 transformers in this series include internal thermal switches. These switches are normally closed and auto resetting. They are internationally approved and listed devices. Transformers from 100 VA to 2000 VA have a thermal device in series with each primary winding. 3000 VA to 12500 VA transformers have a single low current device, with separate lead-outs, for connection to a relay, or similar disconnect circuit.
Type 3 transformers in this series do not include internal thermal protection devices. These transformers are intended for use in medical applications where protective devices are external to the transformer (i.e.: fuses, circuit breakers and thermal cutouts.) See selection table and schematics. |
| Protective Earth Conductor | Type 1 transformers in this series include a conductive copper foil (5 mil) screen between primary and secondary windings. This is a safety requirement for IEC601 Class I equipment. It also provides significant attenuation of high frequency noise.
Type 2 and 3 transformers in this series do not include a protective earth conductor, and are intended for use in IEC601 Class II equipment. See selection table. |
| Magnetic Shielding | All transformers in this series include a shield to attenuate stray magnetic fields. Multiple layers of high permeability silicon steel are laminated with insulation and mounted around the circumference of the transformer. As toroids are already about 1/10th the radiated field of conventional transformers, this additional shielding makes them magnetically silent. |
| Leakage Current | Special design and winding techniques unique to Plitron allow this series to have leakage currents well below international medical safety requirements. This allows margin for line cords and other peripheral components. Measurements are made between the primary windings and all other leads (secondary windings, and ground screen, where used) normal polarity, neutral closed. See ratings table for nominal values. |
| Capacitance | Low interwinding capacitance provides good high frequency common mode noise rejection. Measurements are made using the same method as for leakage. See ratings table for nominal values. |
