tarun172
New User
- Location
- Ottawa, Ontario
- Occupation
- Hardware Engineer
For full transparency, I posted a similar question in EEVBlog but have not received a reply yet. I feel this question is more appropriate for this forum: https://www.eevblog.com/forum/chat/ul-497a-vs-ul-497b-are-these-surge-protectors-interchangeable/
Here is my question on UL 497-rated devices: I’m replacing an obsolete UL 497A-rated device. The manufacturer recommends a UL 497B-rated part with a higher surge rating, but I’m not convinced they’re interchangeable.
UL 497A is intended for secondary protection, typically located near the protected equipment. Devices in this category are tested for lower surge levels and are designed to coordinate with upstream primary protectors.
UL 497B is intended for primary protection, usually at the service entrance, and is tested to handle higher surge currents.
Therefore, the devices are not automatically interchangeable. There are additional considerations such as clamping voltage, let-through energy, and impedance matching, but I’m keeping this explanation simple.
Am I misunderstanding anything?
Thanks,
Tarun
Here is my question on UL 497-rated devices: I’m replacing an obsolete UL 497A-rated device. The manufacturer recommends a UL 497B-rated part with a higher surge rating, but I’m not convinced they’re interchangeable.
UL 497A is intended for secondary protection, typically located near the protected equipment. Devices in this category are tested for lower surge levels and are designed to coordinate with upstream primary protectors.
UL 497B is intended for primary protection, usually at the service entrance, and is tested to handle higher surge currents.
Therefore, the devices are not automatically interchangeable. There are additional considerations such as clamping voltage, let-through energy, and impedance matching, but I’m keeping this explanation simple.
Am I misunderstanding anything?
Thanks,
Tarun