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Industrial Automation Appliance Accessory Working Principle

Jun 22, 2017

Industrial Automation Appliance Accessory working principle

Industrial Automation Appliance Accessory is a very important part of the relay family, the production of the use of more frequent, has a very important significance. Electrician experts will introduce the work of the so-called thermal overload relay

In the Industrial Automation Appliance Accessory, heat generating elements that produce thermal effects should be connected in series to the motor circuit so that the industrial automation equipment fittings can directly reflect the motor overload current. Industrial Automation Appliance Accessory sensing components, the general use of bimetal. The so-called bimetallic, that is, the two linear expansion coefficient of different pieces of metal to mechanical rolling to form a one. Expansion coefficient known as the active layer, the expansion coefficient of small known as the passive layer. The bimetallic sheet is linearly expanded by heat, and since the linear expansion coefficient of the two layers of metal is different and the two layers of metal are closely bonded together, the bimetal is bent toward the side of the passive layer, and the bimetallic sheet is bent The mechanical force will drive contact action. Common JR36 is the use of this principle.

There are four kinds of bimetallic heating methods, namely, direct heating type, indirect heating type, composite heating type and current transformer heating type. Directly heated by the bimetallic as a heating element, so that the current directly through it; indirect heating element from the resistance wire or tape made around the bimetal and bimetallic insulation; composite heating between the above Between the two ways; current transformer heating element is not directly connected to the heating circuit in series, but connected to the secondary side of the current transformer, this method is more used for large motor current occasions to reduce the heat Component current.

Industrial Automation Appliance Accessory with disconnection protection

Three-phase motor of a wiring loosened or a fuse fuse, is caused by three-phase asynchronous motor burn one of the main reasons. If the motor is protected by the industrial automation equipment accessory, the other two phase currents will increase much when the line is de-energized. Since the line current is equal to the phase current, the current flowing through the motor windings and the flow through the Industrial Automation Appliance Accessory to increase the proportion of the same current, so the ordinary two-phase or three-phase Industrial Automation Appliance Accessory can be protected. If the motor is delta-connected, the phase current and the line current are not equal, the current flowing through the motor winding and the proportion of the current flowing through the industrial automation equipment are not the same, and the thermal element is connected in series Motor power into the line, according to the motor rated current that is set to line current, set the value of a larger. When the fault line current reaches the rated current, within the motor windings, the current current of the larger phase of the fault current will exceed the rated phase current, there is the risk of overheating. So △ connection must be used with phase protection of Industrial Automation Appliance Accessory.

Industrial Automation Appliance Accessory with phase-breaking protection add a differential mechanism based on the accessories of general industrial automation equipment, and compare the three currents. The principle of the differential phase-failure protection device is shown in Fig. The guide plate of the industrial automation equipment part is changed to the differential mechanism, which is composed of the upper guide plate 1, the lower guide plate 2 and the lever 5, all of which are connected by a rotary shaft.

At this point the three-phase bimetallic are heated to the left bending, but the bending deflection is not enough, so the lower guide to the left to move a short distance, the relay does not move. Figure 3c is the case where the three phases are overloaded at the same time, and the three-phase bimetal is bent at the same time to push the lower guide plate 2 to the left, and the normally closed contact is immediately led by the lever 5.