Fuse - solution - Huaqiang Electronic Network

Industrial Router Crystal 3.2*2.5mm 3225 26M (26.000MHZ) 12PF 10PPM 20PPM 30PPM

Crystal oscillator

1.5PF SOT23-6 Low Capacitance 5V Breakdown Voltage 6V SRV05

Photocoupler

The fuse is very easy for our electrician first brother. The small power uses a few thin copper wires, and the big ones use thick copper wire. If it bursts, it will be replaced by a big one. Our textile mills don't use too many fuses in recent years, let's take our factory! Two kinds of fuses for high-voltage power distribution room, RN2 0.5A fuse for high-voltage voltage transformer, and 3.15ARN2 fuse for transformer for 30KVA power distribution room. The low-voltage power distribution room has only 1A RT14 fuse for secondary control loop and 50/63A capacitor protection fuse for capacitor cabinet. The workshop also only has the distribution cabinet RT0 200A fuse and the secondary control 2-10A RT14 fuse. Quick-break fuse for transistor protection for HY492 inverters. Other fuses are replaced by high voltage vacuum circuit breakers, low voltage 100-3200A high performance low voltage circuit breakers and 1-32A miniature circuit breakers.

Figure 4 fuse inverse time characteristic curve

Each melt has a minimum melting current. The minimum melting current is also different depending on the temperature. Although this current is affected by the external environment, it can be ignored in practical applications. Generally, the ratio of the minimum melting current of the melt to the rated current of the melt is the minimum melting coefficient. The melting coefficient of the common melt is generally between 1.1 and 1.5, which is generally considered to be greater than 1.25, that is, the melt having a rated current of 10a is When the current is less than 12.5a, it will not blow.

6.2 Selection method

The rated current of the fuse melt can be selected as follows:

(1) When the smooth load without starting process is protected, such as lighting lines, resistors, electric furnaces, etc., the rated current of the melt is slightly greater than or equal to the rated current in the load circuit.

(2) Protecting the motor melt current of a single long-term operation can be selected according to the maximum starting current, or can be selected as follows:

Ir ≥ (1.5~2.5)ie

Where ir - the rated current of the melt; ie - the rated current of the motor. If the motor starts frequently, the coefficient in the formula can be appropriately increased to 3~3.5, which should be determined according to the actual situation.

(3) Protecting multiple long-term motors (power supply trunks)

Ir ≥ (1.5~2.5)ie max+σie

Ie max - the rated current of the largest single motor. Σie The sum of the rated currents of the remaining motors.

In order to prevent the occurrence of over-level fuses and expand the scope of accidents, the fuses of the upper and lower levels (ie, the power supply dry and branch lines) should have a good fit. When selecting, the rated current of the fuse of the upper (supply mains) fuse should be about 1.6 times that of the lower level (supply branch).

7 Conclusion

I fully understand the characteristics of the fuse, which is familiar to the little things that I don't know very well, so that it can serve us better and more qualifiedly.