Telemecanique Snap Action Limit Switch: 1NC + 1NO Contacts Selection Guide
Why speed-independent switching matters on a PLC input, and when slow break is the better answer.
Telemecanique Limit Switches We Stock
OsiSense XC and OsiSwitch bodies with snap action contact blocks, supplied across India.
Telemecanique Snap Action Limit Switches
Snap action describes how the contact changes state, not how the switch is actuated. In a snap action mechanism a spring stores energy as the actuator moves, then releases it suddenly, throwing the contact across at high speed regardless of how slowly the actuator was pushed. The alternative, slow break, moves the contact at whatever speed the actuator moves.
Why speed independence matters
A slow-moving actuator on a slow break contact produces a slow contact transition. That means a long arc on opening, contact erosion, and — on a PLC input — a period of electrical ambiguity where the input may read as chatter or produce multiple counts.
Snap action removes this. The transition time is fixed by the spring, not by the machine, so a conveyor creeping into position at 5 mm/s produces the same clean edge as one arriving at full speed. This is why snap action is the default specification for PLC position inputs.
Contact arrangements
The most common configuration across the OsiSense XC range is 1NC + 1NO snap action, found on references such as XCKP2118M12, XCKN2118P20, XCMD2102C12 and XCKP2145N12, with terminals marked (13-14) NO and (21-22) NC. Single changeover (1 C/O) snap action is available on XCKJ110513H29, and 2 C/O on XCRT115 and XCRT215.
XE2p contact blocks are rated AC-15 A300 at Ue 240 V, Ie 3 A with Ithe 10 A and 500 V rated insulation. XE3p blocks are rated AC-15 B300 at Ue 240 V, Ie 1.5 A with Ithe 6 A and 400 V insulation.
Snap action with positive opening
A common misconception is that snap action and safety are incompatible. They are not. Telemecanique states that European standard products generally feature positive opening contacts even in snap action versions, which allows their use in safety applications.
Positive opening means the NC contact is forced open by direct mechanical action from the actuator, not by spring return — so a welded contact or a failed spring cannot leave the circuit closed. It conforms to IEC 60947-5-1 and is marked with the standard positive opening symbol.
When to choose slow break instead
Slow break is preferred where the switching sequence must be controlled — break-before-make on changeover contacts to prevent momentary short circuits between two circuits, and applications where a deliberately gradual transition suits the load. Slow break is also used in some safety architectures where a defined overlap or sequence is required.
Contact block ratings
| Block | Utilisation | Ue | Ie | Ithe | Insulation |
|---|---|---|---|---|---|
| XE2p | AC-15 A300 | 240 V | 3 A | 10 A | 500 V |
| XE3p | AC-15 B300 | 240 V | 1.5 A | 6 A | 400 V |
| XE2p | DC-13 Q300 | — | — | 10 A | 500 V |
| XE3p | DC-13 R300 | — | — | 6 A | 400 V |
All OsiSense XC models carry IEC/EN 60947-5-1, UL 508 and CSA C22.2 No 14 approval, with CCC on selected references.
Telemecanique products in stock at IndustryPapa
We are a Telemecanique Sensors stockist in India. OsiSense XC limit switch bodies and heads are supplied to order against your reference; the products below are held on the site and can be ordered directly.
Telemecanique position and safety switches
XCSLF SeriesMetal safety switch, 4 NC + 2 NO, slow break, 3 entries tapped M20, 24 VView product →
XCSE SeriesMetal safety switch, 2 NC + 1 NO, slow break, 2 entries tapped M20, 24 VView product →
XCSE731122Metal safety switch, 2 NC + 1 NO, slow break, 2 entries tapped Pg 13, 24 VView product →
Full Telemecanique range on site
| Reference | Type | Description |
|---|---|---|
| XCSLF Series | Safety interlock switch | Metal body, 4 NC + 2 NO, slow break, M20 entries |
| XCSE Series | Safety interlock switch | Metal body, 2 NC + 1 NO, slow break, M20 entries |
| XCSE731122 | Safety interlock switch | Metal body, 2 NC + 1 NO, slow break, Pg 13 entries |
| XT218A1PCM12 | Capacitive proximity sensor | Cylindrical M18, plastic, Sn 8 mm, 12-24 V DC |
| XT230A1PAL2 | Capacitive proximity sensor | Cylindrical M30, cable connection |
| XUM8APXBL2 | Photoelectric sensor | Miniature photoelectric detection |
| XUYFANEP40015 | Photoelectric sensor | Fork sensor, 40 mm slot |
| XUVE04M3KSNM8 | Label sensor | Transparent label detection, M8 connector |
| XUVU06M3KSNM8 | Label sensor | Ultrasonic label detection, M8 connector |
Frequently asked questions
What does snap action mean on a limit switch?
Snap action means an internal spring stores energy as the actuator moves and releases it suddenly, so the contact changes state at a fixed high speed regardless of how fast or slow the actuator was moved. This gives a clean, fast electrical edge.
Is snap action better than slow break?
For most PLC position sensing, yes — it removes contact chatter and reduces arcing when the machine moves slowly. Slow break is preferred where break-before-make sequencing is required between circuits, or where a controlled transition suits the load.
Can snap action contacts be used in a safety circuit?
Yes, provided they carry positive opening operation conforming to IEC 60947-5-1. Telemecanique European standard products generally feature positive opening even in snap action versions. Check for the positive opening symbol on the specific reference.
What is the current rating of a snap action Telemecanique limit switch?
It depends on the contact block. XE2p blocks are rated AC-15 A300, Ue 240 V, Ie 3 A, with a thermal current Ithe of 10 A. XE3p blocks are rated AC-15 B300, Ue 240 V, Ie 1.5 A, Ithe 6 A.
Need a Telemecanique snap action limit switch?
Tell us the load, the voltage and whether the input goes to a PLC or a contactor coil, and we will confirm whether snap action or slow break is right and which contact block you need. GST invoicing and pan-India dispatch.
☎ Call +91 99530 39482 WhatsApp EnquiryTelemecanique limit switch dealer and supplier — major cities
We supply Telemecanique OsiSense XC limit switches across India with GST invoicing and same-day dispatch on in-stock items. Local pages for the cities we ship to most:
Not listed? We deliver pan-India. Call or WhatsApp +91 99530 39482 with your reference and delivery pin code.