UL 1577:2000 pdf download Optical Isolators
Scope
1.1 These requirements cover optical isolators, also called optical couplers or photocouplers:
a)Intended to provide unidirectional signal transfer between dielectrically isolated circuits and.
b) Intended for use in equipment with a supply voltage not exceeding 600 V ac rms or dc
1.2 These requirements cover the electrical insulation properties of the insulation between the isolatedcircuits of the optical isolator.
1.3 These requirements also cover double protection optical isolators that are employed in nominal 125V, 50 or 60 Hz circuits in radio, video, and television equipment, and similar equipment in applications inwhich breakdown of the optical isolator may result in a risk of fire, electric shock, or injury to persons.
1.4 These requirements do not cover the electrical properties of the separate circuits of the opticalisolator.
1.5 These requirements apply to optical isolators for use as components in devices and appliancesCompliance of an optical isolator with these requirements does not indicate that the isolator is acceptablefor use as a component of an end product without further investigation.
1.6 A product that contains features, characteristics, components, materials, or systems new or differentfrom those covered by the requirements in this standard, and that involves a risk of fire or of electric shockor injury to persons shall be evaluated using appropriate additional component and end-productrequirements to maintain the level of safety as originally anticipated by the intent of this standard.Aproduct whose features, characteristics, components, materials, or systems conflict with specificrequirements or provisions of this standard does not comply with this standard. Revision of requirementsshall be proposed and adopted in conformance with the methods employed for development, revision, andimplementation of this standard.
2 Glossary
2.1 Dielectric Insulation-Voltage Rating – The maximum voltage-withstand potential between the inputand output circuits of the optical isolator.
2.2 Electrically-lnsulating Optical Medium – A medium between the photo-emitter and photo-sensor thatelectrically insulates them from each other but allows the transmission of light form the photo-emitter tothe photo-sensor, such as an air space, glass, or the like.
2.3 Insulation, Basic – lnsulation applied to live parts to provide basic protection against electric shock
2.4 Insulation, Double – An insulation comprised of basic insulation and supplementary insulation. Adouble protection optical isolator has double insulation.
2.5 Insulation, Supplementary – lndependent insulation applied in addition to the basic insulation inorder to protect against electric shock in the event of a failure of basic insulation.
2.6 Photo-Emitter – A device internal to the optical isolator that generates electromagnetic radiation.
such as a light-emitting diode (LED), used to transmit signals to the photo sensor.
2.7 Photo-Sensor – A device internal to the optical isolator that generates an electrical current due toincident light such as a photo diode or a photo-conductive transducer, used to receive signals from thephoto-emitter.
3 Units of Measurement
3.1 Values stated without parentheses are the requirement. Values in parentheses are explanatory orapproximate information.
4References
4.1 Any undated reference to a code or standard appearing in the requirements of this standard shall beinterpreted as referring to the latest edition of that code or standard.
CONSTRUCTION
5 General
5.1 An optical isolator shall be constructed in compliance with Sections 6 – 9.
6 Corrosion Protection
6.1 lron and steel parts shall be protected against corrosion by enameling, galvanizing, plating, or otherequivalent means.
Exception: Encapsulated parts and stainless steel parts need not be provided with plating.
7 Insulating Materials
7.1 An insulating material shall be investigated in accordance with the applicable requirements in theStandard for Polymeric Materials – Use in Electrical Equipment Evaluations, UL 746C, and shall have athermal index at least equal to the maximum operating temperature of the insulating material.
Exception: lnsulating materials that are encapsulated or hermetically sealed need only be subjected tothe tests in Dielectric Voltage-Withstand Test, Section 11 and, if the generic temperature rating of thematerial is exceeded, to the test switch in Limited Thermal Aging Test, Section 12.