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Switching Power Supply’s Safety Reports and Certifications

Safety mark

Switching power supplies are basically certified to IEC 60950-1. In general, the power supply’s safety reports and certifications are required for the actual installation besides the manufacturer’s datasheet. Failure to follow these can cause delays when system certification is required.

Normally there are three main documents involved: CB certificate, IEC 60950-1 CB report and/ or EN 60950-1 test certificate. For North America, the UL or CSA 60950-1 test report is essential. Due to confidential information like schematics, full test reports are often restricted by the manufacturers and may only be released with a non-disclosure agreement (NDA).

The CB test certificate is always accompanying the CB test report. This certificate details the part numbers of the power supply that have been certified, their input and output ratings along with the safety standard including revisions and amendments. Its function is to give a quick summary of the product and to show if all the certifications are current. A power supply that has out of date certifications may only be suitable where the safety organizations have allowed the use of the product for older systems, and will not suitable for new designs or major system upgrades.

The full CB or UL 60950-1 test report may extend to over 300 pages. The section “Engineering Conditions of Acceptability” has the all-important details for how the product should be used. For example: “Those outputs that are not should be insulated or have their access restricted to ensure that an operator or service technician cannot receive an electric shock.”

To reduce cost, many power supply manufacturers are using the CE Mark to indicate compliance with EN 60950-1 rather than pay for and maintain a separate EN 60950-1 test report and certificate. In this case the CB test certificate and CB test report will indicate that the product was additionally evaluated to EN 60950-1, and this is absolutely acceptable.

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