PLC Analog Input Card - Dielectric Strength & Insulation Resistance Test Values

Hello Experts,

I'm currently reviewing a Customer specification which requires PLC Analog Input Card to have a dielectric strength of 1400 V AC for 1 minute and insulation resistance of 100 MOhms at 500 V DC. My questions are:

- [1] What international standards govern these two requirements?

- [2] Is it correct to state the PLC I/O cards are required to meet only Over Voltage Category II as specified in IEC 60664-1? Does this standard specify any particular limits on the voltages applied during the dielectric strength and insulation resistance tests?

Thanks, in advance, for your inputs!

Regards,

Nishanth N

  • Hi Nishanth, these isolation standards are typically reflected in Underwriters Laboratories (UL) 61010-1 standard. Across the product portfolio, we have isolated and non-isolated analog input cards, and different applications will require different isolation levels. The IC695ALG112 is an example of an Isolated Analog Input card in the RX3i product line. As to the 2nd question, please keep in mind that voltages that are applied to the dielectric are relative to the actual working voltage of the circuit being isolated and the level of protection required. Let us know if we can help with any other questions.