限位開關(guān)是機(jī)電或固態(tài)設(shè)備需要身體接觸開關(guān)的執(zhí)行機(jī)構(gòu)，使接觸狀態(tài)改變的對(duì)象。主要有兩種類型的產(chǎn)品：旋轉(zhuǎn)和直線。旋轉(zhuǎn)限位開關(guān)使用物理驅(qū)動(dòng)的杠桿旋轉(zhuǎn)軸和操作開關(guān)接觸，使他們改變狀態(tài)。線性限位開關(guān)，機(jī)電設(shè)備，需要一個(gè)目標(biāo)對(duì)象和開關(guān)激活之間的身體接觸，使接觸狀態(tài)改變。專業(yè)限位開關(guān)也可提供。
不同類型的開關(guān)和接觸式限位開關(guān)。開關(guān)類型有兩種選擇：機(jī)電式和固態(tài)式。機(jī)電限位開關(guān)，機(jī)械觸點(diǎn)，繼電器，或蘆葦。固態(tài)限位開關(guān)是電子的，沒有運(yùn)動(dòng)部件。有接觸式三種選擇：瞬時(shí)接觸，保持聯(lián)系，并積極開放。瞬時(shí)接觸開關(guān)打開或關(guān)閉僅在驅(qū)動(dòng)。意味著限位開關(guān)觸點(diǎn)觸發(fā)的位置，甚至執(zhí)行器已被釋放后仍然保持著聯(lián)系。的接觸，只有通過進(jìn)一步的操作頭的機(jī)械動(dòng)作復(fù)位。積極開放意味著接觸點(diǎn)打開可靠，則仍然開放，在激活的位置，甚至在機(jī)械故障的情況下，。
正常狀態(tài)和交換機(jī)的配置選擇限位開關(guān)時(shí)要考慮的重要參數(shù)。正常狀態(tài)下有兩種選擇：常開（NO）和常閉（NC）。常開（NO），開關(guān)觸點(diǎn)，在開啟位置時(shí)，中斷電路。當(dāng)啟動(dòng)時(shí)，觸點(diǎn)閉合。常閉（NC），開關(guān)觸點(diǎn)，常閉位置時(shí)，建立一個(gè)電路。當(dāng)啟動(dòng)時(shí)，觸點(diǎn)打開。有交換機(jī)配置的四種選擇：?jiǎn)蔚秵螖S（SPST），單刀雙擲（SPDT）;雙刀單擲（DPST）;和雙刀，雙擲（DPDT）。
限位開關(guān)不同的定位和性能方面。確定上漿要求時(shí)，限位開關(guān)調(diào)節(jié)器的方向是至關(guān)重要的。一些限位開關(guān)有一個(gè)頂部安裝的執(zhí)行機(jī)構(gòu)。其他有側(cè)的限位開關(guān)的執(zhí)行機(jī)構(gòu)。在性能方面，限位開關(guān)進(jìn)行規(guī)格最大額定電流，最大額定交流電壓，直流電壓等級(jí)最高，最小機(jī)械壽命，電氣壽命最低，工作溫度。一些限位開關(guān)晶體管 - 晶體管邏輯電路（TTL）的使用而設(shè)計(jì)。
Limit switches are electromechanical or solid state devices that require the physical contact of an object with the switch’s actuator to make the contacts change state. There are two main types of products: rotary and linear. Rotary limit switches use physically-actuated levers to rotate a shaft and operate the contacts in a switch, making them change state. Linear limit switches are electromechanical devices that require physical contact between a target object and switch activator to make the contacts change state. Specialty limit switches are also available.
Limit switches differ in terms of switch type and contact type. There are two choices for switch type: electromechancial and solid-state. Electromechanical limit switches have mechanical contacts, relays, or reeds. Solid-state limit switches are electronic and do not have moving parts. There are three choices for contact type: momentary contact, maintained contact, and positive opening. Momentary contact means that the switch is open or closed only during actuation. Maintained contact means that the limit switch contacts remain in the triggered position even after the actuator has been released. The contacts are reset only by further mechanical action of the operating head. Positive opening means that the contact-point opens reliably and then remains open, in the activated position, even in the event of a mechanical failure.
Normal state and switch configuration are important parameters to consider when selecting limit switches. There are two choices for normal state: normally open (NO) and normally closed (NC). Normally open (NO) means that the switch contacts, when in their open position, interrupt the circuit. When actuated, the contacts close. Normally closed (NC) means that the switch contacts, when in their normally closed position, establish a circuit. When actuated, the contacts open. There are four choices for switch configuration: single pole, single throw (SPST); single pole, double throw (SPDT); double pole, single throw (DPST); and double pole, double throw (DPDT).
Limit switches differ in terms of orientation and performance. The orientation of the limit switch actuator is critical when determining sizing requirements. Some limit switches have a top-mounted actuator. Others have the actuator on the side of the limit switch. In terms of performance, limit switches carry specifications for maximum current rating, maximum AC voltage rating, maximum DC voltage rating, minimum mechanical life, minimum electrical life, and operating temperature. Some limit switches are designed for use in transistor-transistor logic (TTL) circuit.
