Circuit breaker terminal heat size factors Indirect cause analysis

As an indispensable safety material in the electric power industry, today for you to cite the example of the circuit breaker, as the name implies, is able to cut off the power supply in time when the current overload, to prevent further safety threats to the product, in addition, the later use of circuit breakers is not only inseparable from the selection of materials in the early stage, but also with the product of the wiring method and installation techniques contacted closely. Closely, such as today's example for you is the use of circuit breaker wiring scheme reference, we also further analyze the circuit breaker terminal heat size of the factors and reasons.

A circuit breaker terminal heat indirect causes

Circuit breaker terminals and circuit breaker internal contact system, thermal disconnectors, electromagnetic disconnectors connected through the main circuit, the heat of these three will inevitably pass through the internal metal conductor to the terminal, so it must be contact system, thermal disconnectors, electromagnetic disconnectors Therefore, it is necessary to analyze the contact system, thermal release, electromagnetic release respectively. Contact system including moving contacts and static contacts, the two contact the formation of access, the two separated from the broken circuit, circuit breaker closure, broken circuit is realized through it, its heat and the principle of direct heating of the terminal is exactly the same, the factors affecting the current and contact resistance. Thermal bimetallic striker core element is a bimetal, line overload rely on its heat bending characteristics to break the circuit, so it is easy to heat the characteristics of certain types of circuit breakers but also in the bimetal winding heating wire to strengthen the heat. Electromagnetic disconnector consists of a yoke and armature, the current flows through the coil to form an electromagnetic field, not only the coil resistance loss, but also eddy current loss. The three are the main source of heat inside the circuit breaker, and through the main circuit is connected to the terminals, so the heating of the circuit breaker terminals is not only affected by the resistance of the conductor at the terminals and the contact resistance of the heat, but also by the influence of the heat generating components inside the circuit breaker.

The above direct and indirect causes, in the end, which is more influential. Depending on the situation to analyze. Under normal circumstances, the contact resistance in the normal range, the size of the current is the main influence. Abnormal circumstances, if the circuit breaker terminals at the contact is not good, crimping is not secure, resulting in increased contact resistance, then the contact resistance of the impact of heat will be greatly increased.

From the above analysis, it can be seen that the circuit breaker terminal heat than simply only play a role in connecting the terminal heat is much more complex. For the actual electrical fire detection, the temperature characteristics of the circuit breaker terminal is very worthy of study, after all, more than one factor affecting the temperature of the circuit breaker terminal. Therefore, not only to theoretically analyze the factors affecting its heat, but also to carry out the actual testing of the terminal temperature, for specific data to be analyzed.

Two, affecting the size of the circuit breaker terminal heating factors

The above analysis of the circuit breaker terminal heating mechanism, the starting point for the circuit breaker itself, not considering the heat source outside the circuit breaker, the actual distribution box circuit breakers are side-by-side arrangement, so from the heat, heat transfer and heat dissipation to analyze the impact of the circuit breaker terminals, the main factors include the following Heat factors mainly include the following:

(1) the size of the current

From the thermal effect of the current to analyze, the size of the current is the most important factor, after all, the calculation of the thermal effect of the calculation of the participation in the operation is the square of the current.

(2) contact resistance

From the thermal effect of the current to analyze, the contact resistance is the most important factor alongside the current.

(3)Internal heat source

The influence of internal heat source on the circuit breaker terminal heat is reflected through the heat transfer, the heat transfer efficiency of the metal conductor must be considered.

(4) external heat source

External heat source that is next to the circuit breaker, their impact on the circuit breaker terminal heat has two aspects, one is the heat transfer, and the other is heat dissipation. If the circuit breaker next to the higher load factor, heat generation is obvious, it will affect the near-side of the circuit breaker through heat transfer, at the same time the circuit breaker's own heat dissipation will be affected by the presence of the circuit breaker next to it.

(5) internal cooling space

Circuit breaker internal cooling space on the circuit breaker terminal heat also has a certain impact, mainly through the form of heat embodiment, the smaller the internal cooling space, the more likely to cause heat accumulation, heat accumulation leads to higher temperatures.

(6) the cross-sectional area of the wire and material

The terminal crimp wire cross-sectional area and material is the determining factor of the size of the resistance of the conductor per unit length, can be included in the scope of the current thermal effect, through the heat transfer affects the temperature of the terminal itself.

(7) tightening torque

Tightening torque refers to the fixed circuit breaker terminals when the torque, the size of the tightening torque directly affects the size of the contact resistance, because the contact resistance of the influence of many factors, and most of them are difficult to determine simply, only the tightening torque is more intuitive, and therefore will be used as a separate impact factor.

If the circuit breaker terminals are hot, then it may lead to their safety and security effect is not very satisfactory, and even buried additional hidden danger, resulting in current leakage problems and troubles, so we should choose to understand the circuit breaker terminals similar to the above mentioned reasons for the heat, if similar performance, should be promptly analyzed and troubleshooting, choose a reasonable and reliable program and recommendations. Reasonable and reliable programs and recommendations, and thus start maintenance and repair treatment, so that the value of the circuit breaker itself can be maximized as far as possible, to avoid additional losses and problems.

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