Contents
What rating should a fuse be?
1. NORMAL OPERATING CURRENT: The current rating of a fuse is typically derated 25% for operation at 25ºC to avoid nuisance blowing. For example, a fuse with a current rating of 10A is not usually recommended for operation at more than 7.5A in a 25ºC ambient.
How do you choose a fuse rating for a load?
In order to select the right amperage of the fuse, you first need to know the full-load steady-state current of the circuit at an ambient temperature of 25º C (68º F). Once the current value is determined, then a fuse rating should be selected as to be 135% of this value (taken to the next standard value).
What happen if fuse rating is too high?
If the current flowing through it is too large, the wire heats up and melts. If a fuse with a much higher rating is chosen, it will allow a current much greater than the current drawn by the appliance to pass. This large current will cause the appliance to overheat and be damaged before the fuse blows.
Can you use a 13A fuse in a 3A?
No it won’t. The only difference would be the current that flowed under fault conditions. If the OP replaced the cable on his lamp to a size that could handle at least 13A under normal/fault conditions then he could leave that 13A fuse in place until rapture!
Is it bad to use a higher amp fuse?
Do not replace a blown fuse with one that has a higher amperage rating. The fuse has a specific amperage rating because it is intended to be the weak link in the circuit to protect the electrical components. A blown fuse indicates excessive current has entered the circuit.
When to use a fuse to prevent failure of a MOV?
When subjected to stresses above its ratings, an MOV can fail as a short circuit. If applied conditions significantly exceed the energy rating of the device, and current is not limited, the MOV may be completely destroyed. For this reason, the use of current-limiting fuses is suggested. Q. How do you select a fuse to prevent failure of an MOV?
How are varistors used in an electronics circuit?
MOV a.k.a varistors is commonly used along with fuse in parallel to the circuit that is to be protected. The below image shows how to use MOV in the electronics circuit. When the voltage is within the rated limits the resistance of the MOV will be very high and hence all the current flows through the circuit and no current flows through the MOV.
What happens when a varistor is passed through a MOV?
But, if a high surge (lighting) that is higher in rate that a varistor can handle is passed through it, the component will not perform. The resulting current will be so high that it will damage the MOV. The performance of the varistor will slow down with time even if small surges pass through it.
Which is the maximum working voltage of a MOV?
MOV Specifications Maximum working voltage is the maximum steady-state, DC voltage. Varistor voltage Maximum clamping voltage is obtained when a certain pulse current is applied to the component to obtain a maximum peak voltage. Surge current Surge shift refers to the variation in voltage after a surge current is given.