Switch contacts shall be ed under different load conditions such as resistive load, inductive load and horse-power load
We has accumulated a lot of experience in ing materials for switch contacts in the process of switch development and manufacturing. Now for a variety of load conditions switch contact ion and a variety of load concept for some empirical summary, to share with you, look at the industry colleagues found that there is something wrong, correct at any time!
First of all, appliance switches and electronic switches are basically divided into the following categories of load types according to the different devices applied. We list the ion of switch contacts under various load conditions and the treatment methods:
1.电阻负载 Resistance load
Resistive load refers to the power factor 1(cos =1) when only the resistive load is applied. The rated mark of the switch indicates the current capacity when ac is used. Generally used in switch load testing cabinet, apply for UL.CQC and other product certification, certification body designated as resistance load, resistance load generally refers to the theoretical load 100% power. Only in this way can the basic load parameters of a switch product be given.
The application of switch in resistive load is: oven, electric stove, get hot quickly, water heater and so on should belong to resistive load.
3.白炽灯负载 Incandescent lamp load
When the lamp is lit, set the switch ON, because the instantaneous impulse current is 10 to 15 times of the usual current, the adhesion of the contact may occur, please consider the transition current when ing the switch.
Switches are used for stage lighting, laser lighting, and spotlights. For example, the rated current of light is 5A 220VAC. At the moment when the light starts, the instantaneous current can reach up to 60A. Under such a high load, if the switch contact is ed improperly, or the breaking force of the switch is not strong, it is easy to cause the adhesion of the switch contact, which cannot be disconnected.
4.感性负载 Induction load
In the case of inductive load relays, solenoids, buzzers, etc., an arc caused by the reverse starting potential will be generated, which may cause contact failure. Therefore, it is recommended to appropriate spark to eliminate the arc.
Inductive load is a common load in switching power supply, which will generate transient surge current far beyond the normal operating current, and the surge current can easily reach 8 to 10 times of the steady-state current. When the switch on the inductive load is turned on, the inductor or transformer will sense the reverse voltage in the circuit. This voltage makes any change in the current of the circuit and can reach several hundred volts. Such a high voltage can prevent the corrosion of the switch contacts arc, play a role in self-cleaning. Under the same conditions. The dc inductive load is more corrosive to the switch contacts, so the dc inductive load should be ed at a higher level than the ac. Electric motor, electric welding machine, refrigerator, air conditioner, electric fan, range hood, electric drill and so on are inductive load.
5.电机负载 （马力负载）Motor load
When the motor is started, the starting current flowing through is 3 ~ 8 times of the usual current, so contact adhesion may occur. The type of motor varies, but the current flowing through is several times the nominal current, so please refer to the values shown in the table below when ing the switch.
In addition, when the motor is rotated in the reverse direction, it is necessary to consider that the multiplied current (starting current + reverse starting current) should be avoided when the on-off-on switch is used.
The motor type
Three-phase induction motor box type
The current recorded on the plate is about 5 ~ 8 times
Single-phase induction motor split phase start type
The inscription plate records about 6 times the current
The current recorded on the plate is about 4 ~ 5 times
Rebound start type
||The plate records about three times the current|
In the case of reverse rotation during rotation, the current flowing is about twice as much as the starting current. In addition, it is used for load with transition phenomenon, such as motor reverse rotation operation, or heteropolar switching, etc. Due to the influence of time delay, arc short circuit (circuit short circuit) may occur between the poles when switching.
There is a misunderstanding between the horsepower load and motor load. In fact, when the switch shell is labeled, it is often seen that 30A 250VAC refers to the load at the beginning of the relay.
1/2HP is the concept of power! About 1250 w.
1 horse (HP)=2500W, which is strictly defined as 2499W in Japan, and calculated according to the energy efficiency ratio EER.
1 horsepower =735W, a horse is defined as the amount of power generated by the input of 1 horsepower. There is a question of coefficient, which is 3.4 according to the Japanese regulation, and 3.4 is the minimum energy efficiency ratio that should be adopted.
So 1 horse =735*3.4=2499W
6.电容负载 Capacitor load
Under the capacitive load of mercury lamp, fluorescent lamp and capacitor circuit, when the switching circuit is connected, it will flow through a very large impulse current, sometimes reaching 100 times of the stable current. Therefore, please use the actual load to measure its transition value and confirm whether it is used in the range without exceeding the rated current, and then use it after using the actual load to confirm. Electronic devices such as televisions and computers should be capacitive loads.
7.微小型负载 Mini Load
Switch contacts used in the field of small loads, if not specifically labeled, are silver or silver alloys. Therefore, due to the change of time and the influence of the external environment, the contact surface is prone to vulcanization and the conductivity may become unstable. For this purpose, in the use of small current, use less frequency, please use gold Au plating or Au plating of the following products.
For example, HONYONE\’s TS series model with light touch switch. Button switch model PB06, PB26 series, etc. Refers to the minimum current under 6mA, the minimum voltage under 3V, the switch only plays the role of the trigger signal, the load it imposed on the switch can be ignored, but it is this kind of micro small switch, is the switch industry is the most difficult to control. HONYONE has accumulated more than 20 years of manufacturing and research experience, and has reached the leading level in the field of micro load switch.