CSA C22.2 NO 205-2017 Signal equipment.
Double-insulated equipment — equipment in which double insulation is used throughout, except for parts where, because double insulation is manifestly impracticable, reinforced insulation is used. Note: Insulating material may form a part or the whole of the enclosure of double-insulated equipment.
Double insulation — an insulation system comprising functional insulation and supplementary insulation, with the two insulations physically separate and arranged so that they are not simultaneously subjected to the same deteriorating influences (e.g., temperature, contaminants, etc.) to the same degree.
Functional insulation — the insulation necessary for the proper functioning of the equipment and for basic protection against electric shock.
Functional safety — safety related to the application that depends on the correct functioning of the safety related functions of the control
Gas sensor/detector — a device that is responsive to a concentration of gas.
Live part — a part with which contact might cause a significant electric shock. A part is live if the open circuit voltage between the part and any other part of the same apparatus exceeds 42.4 V peak and it is capable of delivering a current of 5 mA rms or 7.07 mA peak when measured through a resistive load of
Note: A frequency-compensated leakage current meter Is not to be used to establish whether a part is a live part or not.
Pollution degree — the degree to which pollution is present in the microenvironment surrounding a clearance or creepage distance, classified as follows:
Degree 1 — no pollution or only dry, non-conductive pollution. The pollution has negligible effect.
Degree 2 — non-conductive pollution. A temporary conductivity caused by condensation is normally expected.
Degree 3 — conductive pollution, or dry non-conductive pollution that becomes conductive due to anticipated condensation.
Radium — Ra-226.
1) Radium (Ra-226) is a naturally occurring radioactive solid produced as part of the natural uranium ((.1-238) decay chain. The half-life of Ro-226 is 1600 years. Ra-226 decays predominantly by alpha particle emission to Rn-222, meaning that Ra-226 is the parent of Rn-222.
2) Ro-226 is used in radon chambers as a source of radon gas. These sources ore known as radon generators and are often cylindrical in shape.CSA C22.2 NO 205 pdf download.