Fuse rating for compressor

[VictorPS]

Hi,

In a water system, there is a small compressor that do water cooling.

My question :
I need to add a fuse to protect the compressor.

in normal running, the current is less than 3A, 240V.
When Start up, it can be very high current, but I have no idea how high is it, because it is hard to measure without a proper equipment.

I have try placing a 7A , and even 10A fast blow fuse, but they burn up also after a few days.

For this kind of protection, what proper fuse and proper rating I shall use ?

Thank you,
Victor

 

[bassnut]

use a slow blow fuse (say 5 or 10A), they are made for these applications, or better still, circuit breaker, so you only have to reset on jam ups, not replace fuses.

 

[VictorPS]

I can use slow blow fuse, but for knowledge, how to calculate the safe rating?
Thank you,

 

[dknguyen]

Isn't it usually double the maximum expected rating?

Are those slow blow fuses that are burning up? Because the reason to use slow blow fuses is so they will tolerate spikes during startup and operation but burn out in prolonged overcurrent conditions. BUt if they are already 3x the regular level, won't that mean that a fuse large enough to survive also won't protect it during a failure?