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Blog 26 set 2026 LEMA Electric

Guida al cablaggio di un interruttore a levetta DPDT con inversione di polarità

Un interruttore a levetta DPDT può invertire la polarità applicata a un motore CC a magneti permanenti a due fili scambiando contemporaneamente entrambi i collegamenti del motore. In una configurazione comune a sei terminali, collegare il motore ai due terminali comuni centrali e disporre l'alimentazione positiva e negativa sugli angoli esterni opposti, in modo che le due posizioni dell'interruttore scambino la polarità. La disposizione dei terminali non è universale: identificare i terminali comuni e quelli di commutazione consultando il disegno esatto dell'interruttore oppure utilizzando un multimetro in modalità continuità prima di eseguire il cablaggio. Questa è una spiegazione della topologia del circuito e non un'approvazione all'uso diretto dell'interruttore per un determinato motore. La corrente di avviamento e di rotore bloccato di un motore CC può essere molto superiore alla corrente di funzionamento e il motore costituisce un carico induttivo. Le informazioni sul prodotto LEMA LT2210C riportate in questo esempio indicano valori nominali in CA; non dimostrano che sia adatto alla commutazione di un motore CC. Utilizzare un componente DPDT con una portata nominale in CC pubblicata e adeguata al carico effettivo del motore, oppure un relè, un contattore o un driver per motori con caratteristiche adeguate. Immagine reale del prodotto LT2210C. Identifica un prodotto DPDT a tre posizioni; verificare separatamente lo schema elettrico esatto e la portata nominale per carichi in CC. Significato di DPDT in un circuito di inversione DPDT significa doppio polo e doppia via: l'interruttore controlla due percorsi separati e ciascun polo può collegare il proprio terminale comune a uno dei due contatti di commutazione. In un circuito di inversione della polarità, i due poli cambiano contemporaneamente entrambi i collegamenti del motore. In una posizione dell'interruttore, il positivo viene applicato al terminale A del motore e il negativo al terminale B; nell'altra posizione, questi collegamenti vengono invertiti. Come spiega la guida di SparkFun sui motori CC con spazzole, invertire la polarità della tensione ai capi di un motore CC a magneti permanenti con spazzole ne inverte il senso di rotazione. Un interruttore contrassegnato ON-OFF-ON dispone di una terza posizione centrale a scatto che scollega entrambi i poli. Questa configurazione è spesso utile per un comando manuale...

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Blog 26 set 2026 LEMA Electric

Interruttori di finecorsa: confronto tra i valori nominali dei contatti CA e CC – Guida alla scelta

Un finecorsa non ha un unico valore nominale di corrente (ampere) universale. Il carico ammissibile dipende dal modello esatto, dalla tensione, dall'alimentazione CA o CC, dal tipo di carico, dalla frequenza di commutazione e dalle condizioni di prova definite dal produttore. La corrente nominale dei contatti in CA non può essere trasferita alla CC utilizzando la stessa corrente o convertendo i watt. Prima di collegare un carico reale, verificare i valori nominali riportati per lo specifico blocco di contatti e per l'applicazione prevista. Questa guida spiega come leggere i valori nominali dei contatti in CA/CC e presenta un esempio relativo al modello LEMA LZ5. Non si tratta di un'approvazione generale per tutte le configurazioni LZ5: prima dell'approvazione del progetto, verificare con il fornitore il codice d'ordine, la revisione della scheda tecnica, la configurazione dei terminali, l'ambiente operativo e il carico effettivo. Riferimento del prodotto LZ5 effettivo. L'attuatore e l'alloggiamento raffigurati identificano la famiglia di prodotti, ma non i limiti elettrici di ogni variante. Cosa indica, e cosa non indica, il valore nominale dei contatti Un valore nominale rappresenta un limite stabilito in condizioni di prova specifiche, non una garanzia che qualsiasi carico inferiore al valore di corrente indicato funzioni per tutta la durata di vita richiesta. Leggere l'intera specifica: tensione, corrente, CA o CC ed eventuali categorie di carico o condizioni relative al fattore di potenza e alla costante di tempo. Verificare inoltre se il valore si riferisce alla corrente di chiusura, alla corrente di conduzione o all'interruzione di un carico. Queste condizioni operative non sono intercambiabili. In una macchina, un finecorsa spesso rileva una posizione e invia un segnale a un PLC o a un relè, anziché trasportare direttamente la potenza di un motore. Un ingresso PLC è generalmente un carico di controllo a bassa energia; la bobina di un contattore è un carico induttivo; un motore, invece, presenta un'elevata corrente di spunto. In ciascuno di questi casi, lo stesso contatto dell'interruttore può essere sottoposto a sollecitazioni molto diverse. Se l'interruttore deve soltanto segnalare una posizione, un ingresso di controllo progettato adeguatamente o un relè intermedio possono evitare che l'interruttore sia esposto direttamente alla potenza...

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Blog 26 set 2026 LEMA Electric

Microinterruttore per montaggio su PCB: impronta, saldatura e azionamento

Un microinterruttore per montaggio su PCB non è un componente generico a tre pin con un'impronta universale. Prima di progettare le piste in rame, identificare l'esatta variante dei terminali, verificare il disegno del produttore, individuare i collegamenti COM/NO/NC e lasciare spazio sufficiente per l'attuatore e per la sua corsa completa. In un progetto OEM, l'impronta sulla scheda, il supporto meccanico, il processo di saldatura e le condizioni elettriche di funzionamento devono essere verificati congiuntamente. Questa guida utilizza il modello LEMA KW10-0P come esempio specifico di prodotto. Si tratta di un piccolo interruttore a scatto rapido con terminali PCB diritti; la famiglia illustra inoltre perché i suffissi dei terminali sono importanti. Non copiare l'impronta o il profilo di saldatura di un'altra variante KW10 senza aver prima verificato la corrispondenza con il disegno esatto e la specifica controllata. Riferimento del prodotto KW10-0P effettivo: verificare lo stile dei terminali e l'orientamento dell'involucro rispetto al codice del componente selezionato. Cosa rende un microinterruttore adatto al montaggio su PCB? Un interruttore per montaggio su PCB presenta una geometria dei terminali progettata per inserirsi o collegarsi a un circuito stampato. Questa descrizione, da sola, non specifica se il componente sia destinato al montaggio through-hole, quale parte del terminale debba essere saldata, se il corpo dell'interruttore necessiti di un supporto separato o quali dimensioni debbano avere i fori della scheda. Le famiglie di prodotti possono offrire pin PCB diritti, pin autobloccanti, terminali a saldare, linguette a connessione rapida e terminali per fili. Si tratta di interfacce distinte, non di denominazioni intercambiabili per la stessa impronta. Ad esempio, l'immagine di riferimento dei terminali KW10 distingue i terminali PCB diritti da un terminale PCB autobloccante e da un terminale a saldare. Il suffisso e il disegno esatto determinano quale versione viene fornita. Un pin diritto può dipendere dal PCB e dalla dima per mantenere l'allineamento durante l'assemblaggio; una versione autobloccante può utilizzare una forma diversa del pin. Non bisogna presumere quale versione sia presente basandosi soltanto su una fotografia della parte superiore dell'interruttore. Iniziare dal disegno tecnico, non da una...

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Blog Sep 25, 2026 LEMA Electric

Modulo di ingresso alimentazione vs presa di alimentazione, interruttore e fusibile separati

A power entry module combines two or more mains-entry functions—typically an appliance inlet with a switch, fuse holder or filter—into one panel assembly, while a separate-component design uses individual parts and wiring. The module can save panel space, reduce part count and simplify assembly. Separate components provide more freedom for ratings, service access, heat spacing and supplier choices. The better architecture depends on safety approvals, fuse strategy, EMC needs, panel constraints, production volume and maintenance. This guide compares the choices for OEM equipment. LEMA IPZ-series images are real inlet references; the photographed variants do not establish that every function is integrated. Confirm the exact model and schematic. Comparison table Decision factorIntegrated power entry moduleSeparate inlet, switch and fuseVerify Panel spaceCompact shared cutoutMore distributed areaCutouts, clearances and rear depth AssemblyFewer panel parts and jumpersMore wiring and hardwareWork instructions and inspection points FlexibilityFunctions tied to one modelEach component selected independentlyRatings, poles, fuse and filter options ServiceOne module may be replaced as a unitSingle failed part can be changedAccess, spares and fuse replacement ApprovalsModule evidence can simplify component reviewEach part and assembly relationship reviewedExact certifications and end-product conditions Supply riskGreater dependence on one combined itemMore approved alternatives possibleSecond sources and change control What counts as a power entry module A basic appliance inlet only provides the detachable power connection. A power entry module integrates additional functions in the same housing or coordinated assembly. Possible elements include a line switch, one or two fuse positions, voltage selector and electromagnetic-interference filter. Product naming varies, so the schematic and bill of materials should identify the actual functions. Do not assume a rectangular inlet contains a fuse because a drawer-like feature is visible. Likewise, a fused inlet...

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Blog Sep 25, 2026 LEMA Electric

Interruttore a pulsante a fungo: utilizzi e criteri di selezione

A mushroom push button switch uses a wide, prominent actuator that is easy to locate and press, but head shape alone does not make it an emergency-stop device. Select it by intended command, maintained or momentary action, contact arrangement, color, legend, panel fit, electrical duty and required safety function. A general machine-control button and a compliant emergency-stop operator may look similar while having different latching, reset, contact and certification requirements. This guide separates those uses and provides an OEM selection process. LEMA PBS-series photos are real product references for a domed push-button form; confirm the exact model drawing and approvals before specifying any safety-related function. Selection table DecisionGeneral mushroom buttonEmergency-stop applicationEvidence required PurposeLarge manual commandStop hazardous motion in defined conditionsMachine risk assessment and control narrative ActionMomentary or maintainedTypically latching with deliberate resetExact mechanical action and reset method ContactsNO, NC or changeover as requiredSafety architecture may require specific NC/direct-opening contactsContact diagram and compliance documentation Color/markingChosen for machine conventionGoverned by applicable standards and project rulesPanel design and standard review ValidationFunctional and endurance checksComplete safety-function validationTest plan and recorded results Why the large head is useful A broad actuator is easier to find with a hand, glove or palm than a small flush button. It can suit start, stop, acknowledge, cycle request or other commands where visibility and a generous target area are valuable. The shape can also reduce the precision needed for actuation. That advantage creates a trade-off: a projecting head may be struck accidentally. Consider guards, shrouds, spacing and panel location according to the command. A guard must not make an intended urgent action difficult. Test the layout with representative operators, gloves, lighting and viewing angles. LEMA PBS-series product reference showing...

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Blog Sep 25, 2026 LEMA Electric

Grado di protezione IP degli interruttori a pedale per ambienti di lavoro umidi e polverosi

A waterproof foot switch should be chosen from the complete installed system, not from a product photo or the word “waterproof.” The relevant IP rating applies only to the exact tested enclosure, cable entry, connector and operating condition. Water jets, standing water, metal dust, oil, washdown chemicals and outdoor condensation are different exposures. Define the contaminants and cleaning method first, then verify the switch’s documented IP code, mounting position, cable termination and maintenance plan. This guide explains how to specify a foot control for wet and dusty work areas. LEMA LF-series images provide real product references, but no rating is inferred from appearance. Ask for the controlled datasheet and test evidence for the exact model. IP rating decisions at a glance Environment questionWhy it mattersEvidence to requestCommon mistake Dust type and quantityFine conductive dust differs from coarse dry debrisExact first IP digit and test scopeCalling any covered pedal dustproof Water sourceDrips, spray, jets and immersion are separate testsSecond IP digit, orientation and durationTreating all water exposure as equivalent Cable exitIngress often begins at the gland or connectorCable diameter range and assembly instructionRating the pedal but not the cable assembly Cleaning chemicalsCompatibility is not defined by IP aloneMaterial and chemical-resistance confirmationAssuming washdown detergent is harmless Mechanical damageCracks and impacts defeat sealsInspection criteria and replacement limitsKeeping a damaged enclosure in service What the two IP digits mean The first digit describes protection against access to hazardous parts and solid foreign objects. The second describes protection against water under specified laboratory conditions. Higher digits are not a universal promise for every contaminant, pressure, chemical or installation. The IEC explanation of IP ratings provides the official framework; purchase decisions should use the applicable IEC...

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Blog Sep 24, 2026 LEMA Electric

Interruttore a levetta ON-OFF-ON: applicazioni dei circuiti

A center-off toggle switch has three stable lever positions—ON, OFF and ON—so the middle position disconnects the controlled path while either outer position selects a different circuit state. It is commonly used for forward/stop/reverse requests, raise/stop/lower controls, source selection and manual mode commands. The label describes lever behavior, not the internal terminal map. Pole count, maintained or momentary action, contact sequence, voltage, load and interlocking must all be verified before wiring. This guide explains how to specify an ON-OFF-ON switch without confusing it with ON-ON-ON or momentary variants. LEMA LT3130A images are real product references. Always use the exact model drawing and continuity table for the selected ordering code. Center-off patterns compared MarkingCenter stateOuter positionsTypical use ON-OFF-ONMaintained open/neutral stateTwo maintained selectionsDirection or source selection with a stop position (ON)-OFF-(ON)Maintained centerMomentary both sidesRaise/lower or jog commands (ON)-OFF-ONMaintained centerOne momentary, one maintainedMixed command functions after risk review ON-ON-ONConnected center patternTwo additional connected patternsMulti-circuit selection; not center-off ON-OFFNo third positionOne connected, one disconnectedSimple two-position control Parentheses conventionally indicate spring-return positions, but markings vary. Confirm the mechanical action and circuit diagram instead of ordering from punctuation alone. What happens in the center position In a true center-off function, the relevant moving contact is not connected to either outer throw in the center position. In a single-pole version, a common terminal usually selects one of two throws. In a double-pole version, two independent commons change together. The center may disconnect both poles, but terminal numbering and physical layout differ between families. Center-off does not guarantee galvanic isolation for every circuit or a safety-rated stop. Contact spacing, leakage through other components, shared commons and downstream electronics still matter. If isolation or hazardous-motion stopping is required, use...

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Blog Sep 24, 2026 LEMA Electric

Guida alla posizione di montaggio e alla ripetibilità degli interruttori di finecorsa

Correct limit switch mounting places the actuator where the machine target reaches the operating point consistently, travels far enough to create margin, and stops before the switch is mechanically overloaded. Repeatability depends on the complete system: bracket stiffness, target geometry, approach direction, speed, actuator type, bearing play, temperature, contamination and electrical response. A precise switch on a flexible bracket will not produce a precise machine reference. This guide gives an OEM mounting and validation process using LEMA HL-series products as real visual references. Product photos show the physical family only. Confirm the exact operating position, movement differential, overtravel, allowable force, approach angle and enclosure data from the controlled model drawing. Mounting decisions at a glance DecisionPreferred practiceRisk if ignoredVerification BracketRigid, located by repeatable datumsPosition drift and vibrationDeflection check and torque record ApproachFollow permitted actuator directionSide load, impact or lever damageSlow-motion observation Operating marginTarget passes operating point without exceeding limitIntermittent actuation or overtravelWorst-case tolerance test Target surfaceSmooth, durable and correctly profiledWear, bounce and inconsistent releaseInspection after cycling CableSupported with strain relief and service loopTerminal load or water pathPull and routing inspection Machine referenceDefined independently of switch housingUncontrolled calibration changesGauge or fixture measurement Define what “repeatability” means Repeatability is the spread of switching positions when the same mechanism approaches under the same conditions. It is not the same as absolute accuracy. A switch can repeat closely but actuate at an offset from the desired machine coordinate. A system may also change with approach direction because mechanical backlash, lever friction and movement differential create hysteresis. Write an acceptance statement with units and test conditions. For example: “input changes state within the approved position band during ten forward approaches at production speed and releases...

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Blog Sep 24, 2026 LEMA Electric

Microinterruttore per carichi induttivi: guida alla scelta della portata nominale e delle protezioni

A micro switch for an inductive load must be selected from the load’s making and breaking behavior, not from a resistive current number alone. Solenoids, relays, contactors and small motors can draw inrush current and create a voltage spike when the circuit opens. Those effects can erode or weld contacts, produce electrical noise and shorten service life. The safe method is to identify the actual load, check the exact switch rating for that load category, keep margin, and use a suitable suppression or interface device when the switch data does not directly cover the duty. This guide explains the engineering questions behind that choice. LEMA KW12-series images are used as real product references, but the photographed appearance does not prove a particular inductive-load rating. Confirm the ordering code, datasheet, circuit voltage, current, operating rate and environmental conditions before approval. Why an inductive load is harder on contacts An energized coil stores energy in its magnetic field. When a mechanical contact opens, current tries to continue flowing. The resulting voltage across the opening gap can create an arc. At closing, a motor or transformer may also draw a current higher than its steady-state value. A switch that carries a small resistive heater current comfortably can therefore fail early when used at the same nameplate current with a coil or motor. The problem is not solved by looking only at watts. AC and DC arcs behave differently, coil time constants differ, and the contact material, gap, speed and enclosure all affect interruption. Treat “inductive” as a prompt to obtain the exact switching category and test conditions rather than as a universal derating percentage. Selection table for common inductive duties LoadMain stressInformation requiredTypical...

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Blog Sep 23, 2026 LEMA Electric

AC Power Inlet Fuse Sizing for OEM Equipment

An AC power inlet fuse cannot be selected from the inlet current rating or appliance wattage alone. Start with the equipment’s maximum steady input current at the lowest permitted supply voltage, then evaluate startup inrush, abnormal-load behavior, conductor capacity, fuse time-current curve, voltage rating, breaking capacity, ambient temperature, holder rating and applicable equipment standard. The selected fuse must carry normal operation without nuisance opening while interrupting defined faults safely. A licensed or otherwise qualified designer must confirm the final protective scheme. This guide provides an OEM selection process for a fused AC inlet. It does not prescribe a universal multiplier or a fuse value for a specific machine. LEMA IPZ-series images are product references only; the exact inlet, fuse holder and fuse must be checked as a coordinated assembly. Inputs required before choosing a fuse Design inputWhy it mattersEvidence to collect Supply voltage and frequency rangeChanges operating current and must remain within fuse voltage ratingEquipment input specification Maximum steady input currentEstablishes the normal thermal loadWorst-case measurement and calculation Startup or inrush waveformMay open a fast fuse despite acceptable steady currentPeak current, duration, repetition and temperature Fault current availableMust not exceed the fuse’s interrupting capabilityInstallation or supply-system study Internal conductor and component limitsThe fuse must protect the intended weak pointsWire, PCB, switch, filter and load ratings Ambient and enclosure temperatureChanges fuse carrying capacity and holder heatingWorst-case thermal test Applicable standard and approvalDefines construction, spacing, testing and replacement markingCompliance plan and certified component records If any of these inputs is unknown, the correct action is to measure or obtain it, not to increase the fuse rating until nuisance opening stops. An oversized fuse may leave the cord, inlet, switch, filter or internal...

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Blog Sep 23, 2026 LEMA Electric

Push Button Switch Symbols: NO, NC and Illuminated Types

A push button switch symbol combines two separate ideas: the actuator that a person presses and the electrical contact state that changes. Read the contact in its normal, unactuated and de-energized condition unless the drawing states otherwise. A normally open contact is open at rest and closes when actuated; a normally closed contact is closed at rest and opens when actuated. An illuminated push button also has a lamp or LED circuit, which must be shown and wired separately from the contact circuit. This guide explains how engineers, panel builders and buyers should interpret NO, NC, changeover, maintained, momentary and illuminated push-button symbols. It does not replace the symbol legend, applicable drawing standard or terminal diagram for the exact product. Common push-button symbol meanings Drawing elementMeaning at normal stateChange when pressedTypical verification NO make contactCurrent path is openContact closesCOM–NO continuity appears NC break contactCurrent path is closedContact opensCOM–NC continuity disappears Changeover contactCOM is connected to NCCOM transfers to NOMeter both paths in both states Momentary actuatorReturns when releasedOperates only while force is appliedRelease test through full travel Maintained actuatorRemains in selected stateRequires another action to resetOperate and reset according to drawing Lamp or LEDIndependent indicator circuitIlluminates when its supply is presentCheck rated voltage and LED polarity Graphic details vary among IEC, ANSI and company-specific drawing systems. The project legend governs the drawing. The functional questions remain the same: what is the normal state, what mechanical action causes transfer, which terminals belong to each contact, and what returns the device to normal? LEMA PBS-001 product reference. A product photograph shows construction, while the schematic symbol and terminal drawing define electrical behavior. NO and NC: functional contact sketchesContactAt restWhile actuatedNO — normally...

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Blog Sep 23, 2026 LEMA Electric

Single-Pedal vs Dual-Pedal Foot Switch

A single-pedal foot switch is usually the clearer choice when an operator needs one deliberate command. A dual-pedal foot switch is appropriate when two distinct commands must remain available at the same workstation, such as raise/lower or clamp/release. Pedal count alone does not make either design safer. The machine risk assessment, control logic, guarding, pedal spacing, operating force, cable arrangement and validation determine whether the selected control is suitable. For purchasing, define what each pedal must do in every machine state before choosing the enclosure. This guide compares single- and dual-pedal layouts for industrial and OEM equipment. It uses LEMA LF-series product shapes as real construction references, but it does not assign an unverified safety function, ingress rating or electrical rating to a photographed model. Always confirm the exact ordering code, drawing and test record. Single pedal versus dual pedal at a glance Decision pointSingle pedalDual pedalWhat to verify Number of commandsOne command or one hold-to-run functionTwo clearly separated commandsMachine operating narrative and I/O list Operator choiceLower selection burdenRequires reliable left/right or front/rear identificationPedal spacing, labels and usability trial Control contactsOne contact set or one control channelIndependent contacts or circuits may be requiredExact schematic and continuity test Cable and connectorUsually fewer conductorsMay need separate returns, commons or connector pinsHarness drawing and connector pinout Failure analysisOne actuator to diagnoseCross-wiring and command confusion must be consideredFMEA, commissioning and fault tests Best fitStart, jog, enable or one-direction requestTwo-direction or two-stage operator requestsApplication-specific risk assessment A dual pedal should not be selected merely because it leaves room for future functions. An unused pedal can still be pressed, misunderstood or wired incorrectly. If the equipment only needs one command, a single pedal normally makes the...

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