Watts divided by volts = amps
watts Divided by Volts = amps
A fuse is given a various rating (strength). For instance, a home appliance (washing machine, etc) would usually have a fuse with a 13 amp rating. While a low powered lamp would only merit a 2 or 5 amp fuse rating. It is important to use a fuse of the correct rating in amps for each electrical appliance.
what is the correct fuse rating to provide short-circit protection for a100 HP 200V 3-0 wound-rotor motor
Using a fuse correctly rated for current but "overrated" for voltage does not present a problem. Current ratings are critical safety issues, and fuses should be replaced with those of the same current rating. But using a fuse with an identical current rating but a higher voltage rating is not a problem. The reason for that lies in what the voltage rating of a fuse is. Fuses are given a voltage rating to state a maximum voltage in a circuit that they are designed to protect. And the voltage rating has nothing to do with the "normal" operation of the fuse. The fuse carries current when it operates normally, but when something happens and excessive current flows, the fusible link heats up and opens. This is where the voltage rating comes into play. It is possible that a fuse can arc through when it fails. It is the voltage rating that stands in the way of this. As long as the voltage rating of a circuit is not beyond the voltage rating of the fuse, that fuse will fail safely when it fails. It is acceptable to use a fuse of an equal current rating but a higher voltage rating when replacing a fuse that has failed.
It is ok to use a fuse with a higher amperage rating and not ok to use a fuse with a smaller amperage rating why?
Fuses are rated in amps not watts. You just replace the fuse with one of the exact same amp rating as the one that blew. The fuse is protecting the wiring which you normally cannot change. For that reason you must use the correct rated fuse.
The fuse rating should be 5 amps
The current rating is 2A (2 amps).
Each fuse has its own rating. It will be marked on the fuse somewhere.
A current rating of a fuse is designed to open a circuit at a specific current flow. This rating is imprinted on the fuse and lets you know what the maximum amount of current the fuse is designed to open at. A fuse is in the circuit to protect the conductor that the current flows through. Never over fuse a conductor's current carrying capacity.
A standard 3kW immersion heater will require a fuse rating of 13 A. This is because, it draws a current of 12 A.
Fuses are rated by amperage (current) and voltage. The larger the current need, the larger the rating of the fuse, to handle the current. The voltage rating of a fuse defines the maximum value of circuit voltage in which the fuse can be safely used. A fuse should not be used in a circuit with a voltage exceeding the voltage rating of the fuse.