Abstract

Home use and the specialized level electric appliance uses the electrical machinery although from generally speaking is reliable, but is also easy to receive the mechanical overload, hot, to stop up the extension, the zero curve breakdown, is serious 过电�? the humidity and other damage factors influences. The electric appliance designed the personnel to use each kind of electric circuit preservation technology to strengthen the safekeeping of security ability, avoided the fire risk. At the same time, also reduced because the electrical machinery to have in the warranty period which the breakdown but possibly occurred to repair a second time with the replacement expense.

Technical contrast

Many electric circuits preservation technology main function is protects the electronic circuit not to occur because the oversized electric current or the high temperature has caused damage. In the past, this kind of protection used is the fuse or the fuse, but in the now electrical machinery application, the polymer positive temperature coefficient (PPTC) the component, the ceramics positive temperature coefficient (CPTC) the component and so on may the replacement component as well as the bimetal circuit breaker for the better solution. These may the replacement component not need after to break down to carry on the replacement, and may cause the electric circuit and/or the electric current condition has removed after the power failure restores to the normal working condition. This kind may reposition the function to be able to help the producer to reduce the maintenance, the service and the repair expense. Table 1 pair of overwhelming majority commonly used component replacement function and the electric circuit condition have carried on the contrast.

Although the fuse possibly is the electrical machinery protection is simplest and one of cost lowest solutions, the overwhelming majority producers all believed, if may the replacement protection way be able to be helpful to prevented the electrical machinery because the electric appliance short-circuits, has planted time the electric current damage which or the customer misoperation causes, its cost is reasonable.

The PPTC component uses in simultaneously to prevent because the current surge phenomenon and the excessively hot breakdown causes the damage phenomenon, and has the low resistance characteristic, moreover its size and the fuse solution is also accommodating. Just like the traditional fuse is same, the PPTC component also can limit under the breakdown condition to have the risky big electric current the appearance. However, the PPTC component already removed and the electric circuit power source after the breakdown condition already to separate may voluntarily reposition. This way can guarantee the equipment still was in the function integrity under the condition, and did not need to carry on the fuse replacement or the request service. The CPTC component also is helpful to providing may the replacement protection function, but because it has the relative higher operating temperature, the high resistance number and the great size, its application possibly must be restricted. The CPTC component composition structure also belongs brittle, the thermal load influence which this causes it to be easy which to receive in many electric appliances applications to appear the impact, the vibration or being heated catches cold to damage. The bimetal piece switch although already widely applied in the electric appliance the electrical machinery protection domain, but it could not limit the electric current, and needed to be able to break it through the extra operation to open - closes the circulation. If this kind of component breaks down, it also has the possibility appearance "the breakdown closed" pattern. Other shortcomings weary and are easy including the material to appear the electronic contact to burn down, the spark splash or weld the closed danger. But possibly appears the noise or "�?the clicking sound" as well as the electronmagetic interference (EMI) also has the possibility to create double tinsel shutting and the advanced electronic control system is not accommodating.

But chip solution although has the very good effect, but actually requests to take the bigger board card space and to use many primary devices, including integrated circuit, switch and sensor, thus caused the design complication and increased the design expense.

Swiss �?electric circuit protection department PolySwitch LVR/LVRL the PPTC product series has included the many kinds of rated values is 120 VAC and 240 VAC city electricity product, also may reach 2 in 20°C the under highest operating current to be peaceful. This series product through the UL authentication, may parallel increase the current capacity. These products low costs, may reposition the function and the electric current limit characteristic, causes it to become one kind to be reliable also the economical highly effective protection solution, all similarly is suitable to the intermittent type and the continuous-type movement electrical machinery.

The table1. fuse and may reposition the electric circuit to protect the component to be possible to reposition the function and the electric circuit condition contrast

1 warm electric current protection.

2 hot fuse certainly does not aim at the electric current protection to carry on the design, and usually needs to have the very big electric current to be able to divide breaks.

3 regular attempts replacements operation, until trouble shooting with/or the power source separation, or repositions after bimetal piece cooling to the low resistance condition.

4 once trouble shooting as well as power source separation, then automatic reset to low resistance condition.

Batch operation electrical machinery preservation technology

Batch operation electric motor protection skill

Such as the intermittent type movement electrical machinery usual design which uses in the mixer and food manufacturing machine in the finite time moves, and overall speaking, the running time surpasses the greatest limiting value time usually to be able to cause to stop transfers, has been hot and finally breaks down. Presses down when the switch does not put, because the contact breakdown or the user use not correct all has the possibility to cause the breakdown condition the occurrence.

In order to have prevented the heat, the electric circuit protection component which uses in this kind of situation must be able rapidly to separate, but actually cannot prearrange the speed to be quicker than, avoids to the user creating the disturbance. Developed one kind to be able effectively to protect the electrical machinery but not to be able to have the disturbance separation protection plan already to become in the design work a challenge.

Switch

PolySwitch LVR component

In chart 1. electrical machinery electric circuits model PolySwitch LVR component application

How does chart 2 show for installs a PolySwitch component in the electrical machinery electric circuit, protects the electrical machinery not to have the electric current/hot damage. In this kind of component installs when the electrical machinery, can aim at all temperature rise phenomenon which in the electrical machinery under the electric current mobile condition as well as the malfunction possibly occurs to make the response.

The PolySwitch component manifests in this kind of situation main merit in, it can choose one kind of working current remarkably to be lower than the electrical machinery normal operation electric current the specification, but its operating time may the several fold to the overall system action cycle. This meant, this kind of component can act after certain systems action cycle, but in the electrical machinery electric current achieved the PolySwitch component working current certain time of electric motors stop up transfer under the condition the movement speed actually to be much quicker.

Continuous running electrical machinery preservation technology

These apply to the refrigerator and the air conditioning equipment continuous running electrical machinery has carried on the optimization in the design in view of the size and the expense. Because this kind of electrical machinery usually uses for to actuate the air blower, therefore can have some air currents to carry on the divergence through the electrical machinery, thus lets the pressure which the movement withstands other situations in be higher than. Therefore, the air blower electric motor stops up transfers the electric current usually is only running current 2 times, compares, under other application common ratio for running current 3 time or 4 times. In this kind of situation, must find and determine section can stop up in the air blower transfers the time reliably to shut, moreover cannot first time puts through the power source when the electrical machinery appear the disturbance fuse the fuse product to change extremely complex.

Just like, Poly- which partial discusses in the batch operation electric motor protection the Switch component in the electrical machinery protection plan aspect has provided the remarkable merit. If the electrical machinery is easy to suffer injury the nature to change along with the temperature, then may through change this kind of component the characteristic, in needs in the situation, provides slower response.

By receives the protection in the air blower in the motor-driven application, the PolySwitch component and the electrical machinery passable arrangement has passed the mistake in the air current to obtain the advantage. Under this way, the PPTC component movement magnitude of current will be able to increase, because the air current will tend to cannot let the PPTC component achieve own movement temperature. But, if air blower because any originally thus stops the extension, the air current cooling effect can stop, causing the excess load electrical machinery rapid elevation of temperature. This kind of condition also creates the PolySwitch component movement and the limit passes the electrical machinery the electric current.

Is different with the disposable use fuse, the PolySwitch component is helpful to prevented because the temperature rise but the electric current only has the damage phenomenon which slightly increases causes, only must install the sole part, but simultaneously has provided the electric current and the excessively hot protection function.

The design considers the item

Continuous running electric motor:Regarding estimated the disposable movement surpasses 100 seconds electrical machinery to say, must assign under the ambient temperature according to the electric appliance interior the maintenance electric current to carry on the corresponding component or the component combination. The LVR/LVR component protection electric current must act according to chart 2 in form to reduce the rated value along with the environment operating temperature.

Nominal current percentage (%)

LVR (>0.75is peaceful)

LVRL

LVR (<0.75Peaceful)

Temperature(�?/b>)

Chart 2. LVR and LVRL component typical temperature 折减 rated value curve

Batch operation electrical machinery:Regarding estimated the disposable running time short to 100 seconds electrical machinery, must act according to attempts 3 pair of components to carry on the shaping.

Operating time(second)

Fault current(A)

Chart 3. LVR/LVRL component in 25°C under operating time and fault current relations chart

Wake effect/surface mounting:The air current as well as can remarkably change the working current on the heat conduction surface installment, for example radiator or metal 丝卷. These influences must carry on the computation and the adjustment in the design process. The related concrete application information, please relate Tyco Electronics.

Breakdown condition monitor:The PolySwitch component condition may carry on the monitor through the loss of voltage. Is not in when thiskind ofcomponent limits flows the condition, compares protects the unit the impedance to say that, component impedance extremely small, the component beginnings and ends loss of voltage extremely is also small. Enters after this kind of component limits flows the condition, the component nearly enters leads the way the condition, the component beginnings and ends loss of voltage can increase to is approximate to the power line voltage degree.

In has provided in the controller high-quality electric appliance product, may through realize the monitor function in the control module place connection 1 pair of wiring. In the simpler electric appliance product, the loss of voltage monitor as well as the correct voltage may use in the light emitter diode which shines to the user instruction breakdown condition.

Summary

PolySwitch the LVR/LVRL component product low resistance, the fast operating time as well as may reposition the function the characteristic, is helpful promotes the security and the reliable product to the circuit design personnel, satisfies the management structure the request, reduces the warranty period repair expense. The PolySwitch component product already passed the authentication which the electric appliance designs, and widely applies in the electric appliance design, and conforms to the UL 1,434 standards, and compatibly does not have 铅焊�?and the large capacity assembly craft.

Raychem, PolySwitch and Tyco are a trademark. We believe firmly including instructional diagram all information are reliable unmistakable. But, the user must carry on the independent appraisal to each section product to the user application type compatibility.

The peaceful branch electron company does not make any guarantee to the above information accuracy and the integrity, and refuses to undertake with uses any responsibility which the above information is connected. The peaceful branch electron only duty only includes in this company the duty which stipulated in this product standard sale provision. In any situation, peaceful branch electron regarding because sells, retails, the use or wrongly uses accidental, is indirect or the consequence loss which this product causes does not undertake any responsibility.

The technical parameter like has the change, even slightly not separate informs. In addition, the peaceful branch electron retains to the material and the craft makes does not affect with any is suitable the technical specification tallying revision the right, also does not need to inform the buyer.