Relay is parts of an apparatus of control of a kind of electron, apply in automata circuit normally. Actually it is a kind when go controlling bigger electric current with lesser electric current“Recloser ” .

 

Accordingly, the effect such as self-adjusting, safe protection, change-over circuit is having in circuit. Electromagnetism relay is main by coil, iron piece, the composition such as return spring, movable contact and fixed contact. Common electromagnetism relay the structure sees figure below.

 

Electromagnetism relay is basic structure

 

Electromagnetism relay uses electromagnetism induction principle to have the job:

 

After coil electrify, the core of coil center is produced by magnetization magnetic force and if plan institute shows iron piece suck close, iron piece drive connective through leverage movable contact movement, often open contact to suck right now close, often shut contact to open;

After cutting off coil electric current, core loses magnetism immediately, active force of generation of compressed8 bedspring restoration makes iron piece the reply arrives former position, often open contact to open right now, often shut contact to suck close.

Relay failure mode analysis and countermeasure

 

In circumstance of a few special application, the relay of this should regular job because a variety of special account jobs are unusual, the loss that cause often inestimable. We should be clear when using relay so know to bring about relay the specific reason of invalidation, adopt corresponding settlement then the be no longer in force that measure prevents relay to the greastest extent, this may have great sense to safety of tutelar body, belongings.

 

And to relay, bring about the invalidation reason with its unusual job to have those who amount to 20 kinds, the invalidation reason of the different relay that because particular use environment reachs yard,closes is endless also and same. The article is listed only undermentioned invalidation reason reachs a few kinds of common relay solve countermeasure to consult in order to offer everybody.

 

1-1 contact action is unusual

A. Contact solders: Contact surface carries electricity of big laden surge, electric arc of generation of high frequency numerous switch heats up together with.

 

Correspondence solves measure:

1.Do not make power source voltage drops or coil voltage drops cause contact to vibrate;

2.Notice to shut surge electric current to exceed the load of rated electric current;

3.Notice the tall frequency switch of relay is used.

 

The breakdown contact that generation contact solders – 01

 

The breakdown contact that generation contact solders – 02

 

B. Contact material transfers character: Contact (Ag boiling point is 200° about) electric arc of the generation when undertaking dc load switch is hot (600° ) , bring about contact material to fuse generation evaporates character move.

 

Correspondence solves measure:

1.Reduce laden surge electric current through resistor of series connection current limliting;

2.Diode of contact part paralell connection is absorbed oppose electromotive force.

 

Generation contact is sticky the breakdown contact that changes even capable person character – 01

 

Generation contact is sticky the breakdown contact that changes even capable person character – 02

 

C. Carbide causes contact trouble: Join easily in contact electromagnetism is laden (electromagnetism a powerful person, contactor and valve) when generation, in relay contact leaves for a long time after shutting, contact opens the surge that shut to cause all round of organic gas decompose the carbonization with dirt, adherent go up in contact, then brings about contact the contact is undesirable.

 

Correspondence solves measure:

1.Sensibility turns over electromotive force ladenly to be more than resistor sex load, because this produces carbonization more easily.

2.The surge such as RC of contact part paralell connection or diode absorbs component to absorb oppose electromotive force.

 

The breakdown contact that generates carbide – 01

 

The breakdown contact that generates carbide – 02

 

Afore-mentioned breakdown of 3 kinds of contact should say is us a few kinds of failure mode that in use relay process middling sees, from the contact dependability reachs service life, prevent noise respect regard, the contact that suggests installation uses surge to absorb yuan of parts of an apparatus protects circuit. And, right now, laden release time can have a certain number of delay, real load is used to undertake affirming please before using. In addition, ask an attention, incorrect use meeting causes adverse effect.

 

Protect the typical give a demonstration of circuit for contact below.

1-2 contact protects circuit

A. CR means

 

 

① is in circuit of AC power source, when laden impedance is less than RC impedance, can use.

C: 0.1~1Uf;

R: With laden and equal resistance.

 

 

② all can be used in circuit of power source of AC, DC.

C: 0.1~1Uf;

R: With laden and equal resistance.

 

B. Diode means

DC power source is special. Use the diode of following rating please. Converse withstand voltage: The *10 of power source voltage of laden circuit, to electric current: Be more than load current.

 

 

C. Pressure quick resistor means

All can use in circuit of power source of AC, DC. To get optimal result, when voltage of use 24V~48V power source, in laden end join is pressed quick resistor; When the power source voltage of 100V~200V, between contact join is pressed quick resistor.

 

Note: Do not use the following contact to protect circuit please.

 

This protection circuit is in disconnect arc of the disappear when contact is very effective. But the capacitor when disconnecting as a result of contact (C) meeting labor report, in put through when contact, capacitor pours out of short-circuit current, accordingly, contact appears easily frit is received.

 

 

This protection circuit is in disconnect arc of the offset when contact is very effective. But when contact closes, the contact when the electric current of save up flows to capacitor appears easily frit is received.

 

 

In actual application, almost all relay as a result of,invalidation all is of relay leave often shut bring about its to reach life, or it is to drive high-power sensibility load produces contact to solder thereby or carbonization. Although some had been added,installed the surge protector that waits like diode, but the happening that still cannot put an end to invalidation completely.

 

Accordingly, to those need contact can undertake the control that shut asks really, be like: The signal that stops switch urgently cuts off dynamical source through relay, etc, need to use contain redundant + the safe relay of self check function will undertake coming true. So redundant to taking + how is the safe relay of self check function to return a responsibility after all? Next the relevant knowledge of safe relay does the following introduction to consult for everybody.

 

The definition of safe relay reachs a characteristic

2-1 what is safe relay?

Safe relay is a kind of module that be combined by many relay and logistic circuit and becomes, it is unit of composition of a kind of circuit, its purpose is to want complementary the blemish that each other issue in state of fault, achieve thereby correct and the function of low misoperation, reduce its error and invalidation cost, raise safe element. Whole point says, should call safe relay module.

 

Have different safe risk as a result of different mechanical equipment, different technology segment, reach different dangerous order and degree. Because this is when products plan, designed a variety of safe relay to differ in order to protect grade machinery equipment, main purpose depends on protecting the machinery that exposes the dangerous sex in different grade to operate personnel.

 

The characteristic of 2-2 safe relay

A. Safe relay is module of a kind of circuit is not component of a kind of electron;

B. Safe relay has special color, it is yellow or red commonly;

C. Safe relay differs by the requirement to relay and the subdesign of other logic circuit, diagnose enclothe rate is very high, can achieve a little even 99.9% , because this can be used in a few requirements taller circumstance, the safe relay that also the regulation must use course attestation just can satisfy safe requirement!

D. Safe relay has structure of compulsive oriented contact (other perhaps protection way) , in case when producing phenomenon of solder of contact be in harmony, also can ensure safe, say “ safe relay so ” is not the relay that “ does not have breakdown ” , well-regulated motion is made when malfunctioning however.

 

Compulsive oriented relay

Interiorly directs the action of lever falls compulsively, although contact produces frit form, also won’t make two pairs of contact (NO/NC) appear at the same time ON phenomenon. Compulsive oriented structure is one kind detects the simple and effective kind that contact frit receives breakdown. According to the requirement of EN 50205, in the absolute combination of NO contact and NC contact, when NO contact frit is received, although disconnect relay the power source of coil (without excitation) , NC contact also does not close, ensure the contact clearance of 0.5mm above. In addition, when NC contact frit is received, although start relay the power source of coil (excitation) , NO contact also does not close, ensure the contact clearance of 0.5mm above.

 

The NO contact of compulsive oriented relay is fusible – 01

 

The NO contact of compulsive oriented relay is fusible – 02

 

The NC contact of compulsive oriented relay is fusible – 01

 

The NC contact of compulsive oriented relay is fusible – 02

 

Common relay

If contact produces frit form, can make two pairs of contact (NO/NC) the likelihood appears at the same time ON phenomenon. Say simply: Safe relay more on the safe side, apply to industry to bring whole situation.

 

The applied circumstance of safe relay

A. Applicable and urgent stop pushbutton, below emergency, quit machine movement;

B. Act of applicable and safe light, prevent a staff member to enter critical work limits;

C. Applicable exit is restricted switch, the position of detecting gate, open the application that perhaps closes;

D. The application of switch of applicable electromagnetism door lock, ensure the safety of operation area;

E. Applicable key cooperates exit switch, leave as detecting gate those who shut with;

F. Applicable safety fills up switch, affirm the staff member is OK safety enters dangerous work area.