What is a dual element fuse used for?

What is a dual element fuse used for?

Dual-element fuses sized for motor overload protection can help protect motors against the overload damage caused by single-phasing. See the section “Motor Protection–Voltage Unbalance/Single- Phasing” for discussion of motor operation during single-phasing.

What does dual element fuse mean?

The dual-element fuse provides the same short-circuit current protection as the single-element fuse along with time-delay protection against slow over-currents.

What is the purpose of a dual element time delay fuse?

Dual-element, time-delay fuses provide a time-delay in the low overload range that eliminates needless circuit interruption due to harmless overloads and transient conditions.

What is a dual element circuit breaker?

Sometimes two elements are better than one. Dual element fuses are able to withstand these bursts without inflicting any damage to the motor, circuits, or the fuse itself. Whereas if a single element fuse was used, it would have to be rated up to 3 times the actual motor current in order to withstand these surges.

How do you size a dual element fuse?

To calculate the maximum size dual element fuse allowed for a 10 HP, 230 VAC, 3-phase motor, determine the full-load current using Table 430.250. Then, multiply the value, 28A, by 175%, 28A x 1.75 = 49A. Dual element fuses do not come in a standard size of 49A, Table 240.6(A).

Do fuses provide short circuit protection?

The fuse is ideal for protection against short circuits. Short circuits produce enough amperage to vaporize a fuse element and break connection in one cycle of a 60-cycle system. Fuses are more commonly used in devices connected to a system than within the system’s circuit.

What tool is used to remove cartridge fuses from a fused disconnect box?

What tool is used to remove cartridge fuses from a fused disconnect box? plastic or fiberglass style fuse puller. When a fuse is blown: it must be replaced.

How many ohms should a good fuse read?

Place one of the multimeter leads on one end of the fuse. Place the other lead on the other end of the fuse. If the reading is between 0 and 5 Ω (Ohms), the fuse is good. A higher reading indicates a bad or degraded fuse.

What kind of Fuse is used for branch circuit protection?

Fuses and circuit breakers are used for motor branch-circuit short-circuit and ground-fault protection. Dual element (time delay) fuses and inverse time circuit breakers are the two most common types used to protect motor branch-circuits.

How many fuses does a three phase motor need?

Thus, a three-phase motor requires three fuses. Keep in mind that these devices are at the load end of the branch circuit and they do not provide short-circuit and ground-fault protection.

What is the nontime delay fuse for a 3 hp motor?

(a) The branch-circuit short-circuit protection (nontime delay fuse) for a 3-hp, 115V, 1Ø motor shall not exceed 110A. (b) The branch-circuit short-circuit protection (dual-element fuse) for a 5-hp, 230V, 1Ø, motor shall not exceed 50A.

How to calculate maximum fuse size for 10 hp motor?

To calculate the maximum size dual element fuse allowed for a 10 HP, 230 VAC, 3-phase motor, determine the full-load current using Table 430.250. Then, multiply the value, 28A, by 175%, 28A x 1.75 = 49A.