What could be causing blowing out of fuses 20Amp. in an Atlantis compressor (Copelametic)?

Question

This is a Dental air compressor.

Answer 1

If the 20A fuse is the size that is designed for the machine, then something is wrong with the machine.

Most likely, either accumulated dirt, or worn out parts, or both, are causing the load on the motor to be much higher than designed. If you continue to operate the compressor in this way you will burn out the motor. I looked a little bit for on-line info about the compressor you mentioned but could not find it. If it is old, and replacement parts are not available, you may need to replace the compressor.

One possible transient cause could be a much lower than normal supply voltage - a brownout. If this is happening, the motor will draw more current and possibly blow the fuse. If this is the problem, the solution is to correct the power supply (if it is under your control) or to wait until it is normal again (if it is a utility supply).

Answer 2

If the fuses blow on startup, the inrush current greatly exceeds the fuse rating.

If they blow after a period of running, the running current somewhat exceeds the fuse rating.

If the fuses blow on startup, you could try a slow blow fuse.

If they blow after a period of running, a fuse with larger current capacity is indicated. Of course the wire sizes should be capable of carrying the current.