USBcount50 USB Frequency/Period Counter
Frequently Asked Questions : Isolation
What does the 300V Cat II isolation rating mean?
This means that for a Cat II installation (domestic power outlets, lab use and so on) the USBcount50 can be used with a potential difference between the ground clip and the PC's ground of 300V RMS (or DC), which in the above types of environment could see voltage transients of up to 2500V. This does not mean the count will keep working properly with such large voltage spikes across its isolation circuit, but it does mean that the count will isolate the PC (and you) from seeing the large and dangerous potentials.
What are the safety implications of measuring large voltages?
Always read the USBcount50 Safety advice that can be sound in the User's Guide. Always follow this advice. You are also advised to select scope probes that are at least 300V Cat II rated and you should be aware that fully insulated scope probes are a good idea for such measurements because the ground clip and the BNC's ground could all be at a hazardous potential.
If I stack two or more USBcount50s, are the channels isolated from each other?
No, they share a common ground potential. But they are all still isolated from the PC.
