The nominal power draw should be in the manual, the label on the back of the device and/or is printed on the equipment fuse. However, inrush current when turning on can exceed this very much and the FAQ on equipment fuses gives some insight even if in your case it is the breaker:
However, at the instant that a transformer is first connected across the mains (unit switched on) a transient current up to 10 to 50 times larger than the rated transformer current can flow for several cycles.
The inrush current *** will depend on the transformer characteristics and the point on the power curve at which connection is made to the AC source. If the transformer core retains any residual magnetism the inrush may well be even more severe.
i.e., waiting some time after turning off before you turn on again may help. Giving the power button a decisive push instead of a slow dithering one may also help. Plus, or course, keep it on in the first place most of the time (though some say turning it off for half an hour every few months is good for SQ and I am afraid I had the same experience - don’t ask me for an explanation 
)
The equipment fuses are of the “slow” type to survive this inrush, and even then it is occasionally marginal depending on circumstances of turning on. The regular German breakers seem to be just a bit more sensitive
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