TECHNICAL TERMINOLOGY & CAUTIONS FOR USE Technical Terminology & Cautions for Use
TECHNICAL TERMINOLOGY 1. Rated values 6. Withstand voltage 13. Overtravel (O.T.) Values indicating the characteristics and Threshold limit value that a high voltage The distance which the plunger or the performance guarantee standards of the can be applied to a predetermined actuator is permitted to travel after snap-action switches. The rated current measuring location for one minute actuation without any damage to the and rated voltage, for instance, assume without causing damage to the insulation. switching mechanism. specific conditions (type of load, current, 7. Contact resistance 14. Movement Differential (M.D.) voltage, frequency, etc.). This indicates the electrical resistance at The distance from operating to release 2. Mechanical life the contact part. Generally, this resistance position of the plunger or the actuator. The service life when operated at a preset includes the conductor resistance of the 15. Operating Position (O.P.) operating frequency without passing spring and terminal portions. The position of the plunger or the electricity through the contacts. (The life 8. Vibration resistance actuator when the traveling contacts test is performed at a switching frequency Malfunction vibration ... Vibration range snaps with the fixed contact. of 60 times/minute and operating speed of where a closed contact does not open for 16. Free Position (F.P.) 100 mm/second at the regular cam.) longer than a specified time due to Position of the switch plunger or the 3. Electrical life vibrations during use of the snap-action actuator when no force is applied to. The service life when the rated load is switches. 17. Overtravel Position (O.T.P.) connected to the contact and switching 9. Shock resistance The stopping position of the plunger or operations are performed. (The life test is Shock durability ... Shock range where the actuator after total travel. performed at a switching frequency of 20 the mechanical shocks received during 18. Release Position (R.P.) times/minute and operating speed of 100 snap-action switches transport and The position of the plunger or the mm/second at the regular cam.) installation do not damage the parts or actuator when the traveling contact 4. Contact form harm the operating characteristics. snaps back from operating position to its This refers to the components Malfunction shock ... Shock range where original position. determining the type of application which a closed contact does not open for longer The following terminologies are applied make up the electrical input/output than a specified time due to shocks to all our switches. circuits in the contact. during use of the snap-action switches. R.F. 10. Operating Force (O.F.) O.F. NC Switching The force required to cause contact P.T. T.F. COM T.T. type NO F.P. snap-action. It is expressed terms of O.T. M.D. Normally force applied to the plunger or the NC O.P. R.P. closed type COM actuator. T T.P. Normally 11. Release Force (R.F.) COM open type NO The force to be applied to the plunger or the actuator at the moment contact snaps Terminal symbols COM: Common terminal back from operated position to NC: Normally closed terminal unoperated position. NO: Normally open terminal 12. Pretravel (P.T.) 5. Insulation resistance Distance of the plunger or the actuator Resistance between noncontinuous movement from free position to operating Center of mounting holes terminals, terminals and metal parts not position. carrying current, and between terminals and the ground. CAUTIONS FOR USE Technical Notes on Mechanical Characteristics
1. Actuation Force and Stroke may cause actuator damage due to OF Adequate stroke setting is the key to high inertia of the drive mechanism. It is reliability. It is also important that advisable that the stroke be adjusted with RF adequate contact force be ’maintained to the mounting plate or driving mechanism. ensure high reliability. For a normally The figure at right shows a typical FP RP OP TTP Stroke closed circuit, the driving mechanism example of activation and contact forces PT MD OT should be set so that the actuator is varying with stroke. In the vicinity of the NC Contact force Operating force normally in the free position. For a O.P. and R.P., the contact force is On FP normally open circuit, the actuator should diminished, causing chatter and contact On reversal be pressed to 70% to 100% of the bounce immediately before or after On reversal Stroke On OTP specified stroke to absorb possible reversal. For this reason, use the switch NO errors. while giving due consideration to this. If the stroke is set too close to the This also causes the snap action switch operating point (O.P.), this may cause to be sensitive to vibration or physical unstable contact, and in the worst case impact. ds_62003_en_micro_switches_technical_information: 010314J 1 TECHNICAL TERMINOLOGY & CAUTIONS FOR USE 2. Changes in Operation speed, activation rate, and activation 4. Driving Mechanism Characteristics frequency. Use of a driving mechanism which will Exercise design care so that 1) An extremely slow activation speed cause physical impact to the actuator malfunctions will not occur if the snap may cause unstable contact transfer, should be avoided. action switch characteristics vary by as possibly resulting in contact failures or
Technical Notes on Electrical Characteristics 1. The snap-action switch is designed for 3. Application to Electronic Circuits 6. Ratings are measured under the AC operations. While it has small contact 1) The snap-action switch contacts can following conditions: gaps and no arc absorber, it may be used sustain bounce or chatter when closed. Inductive load: for low-capacity DC operations. Bounce or chatter can cause noise or Power factor = 0.6 to 0.7 (However, a DC magnetic blow-out pulse count errors when the snap action Time constant = 7 ms or less (DC) switch is available in the NZ Basic switch is used in electronic circuits. 7. To prevent contact fusion failure, be switches.) 2) If contact bounce or chatter poses sure to use a serial resistance for each 2. For applications with very small problems in the vicinity of the O.P. and capacitive load. switching voltage or current, choose the R.P., use a suitable absorption network, 8. If snap action switch operation is dry circuit type. such as a C/R network. synchronized with the AC supply phase,
Small current and voltage Application Range 4. Check the surge current, normal this may cause: shortened electrical life, (Dry Circuit type) current and surge duration. contact fusion failure, contact transfer, or 5. Contact resistance given in other reliability problems. 500 performance specifications is measured with a voltage drop method using 6 to 8 V
100 DC, 1 A (except for low-level load type).
50 Contact resistance across COM and NC
Current (mA) terminals is measured in the open position, while contact resistance across 10 COM and NO terminals is measured in 5 the closed position.
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1 4 8 12 16 20 24 DC voltage (VDC) Cautions in a circuit 1. Contact protection is recommended 2. Do not connect the contacts on Example of wrong power supply when snap-action switches are used in individual switches to different type or connection (connection to different an inductive load circuit. (except for NZ different poles of the power supply. poles of power supply) Basic Switches magnetic blow-out types Examples of power supply This may lead to mixed DC and AC. for DC) connections (connection to different Wrong poles) Load Circuit diagram Notes L Wrong AC 1. r = more than 10 Lamp load ohms PL 2. In an AC circuit. DC Impedance of L is rc R to be slightly
smaller than Solenoid load impedance of r and Right c. Lamp load Load L Can be used for both PL AC and DC circuits. Impedance of r is 3. Avoid circuits which apply voltage r R nearly equal to between contacts. (This may lead to c impedance of L. Solenoid load mixed deposition.) C: 0.1 μF Load connected to same pole Wrong
diode R For DC circuits only.
L 200V
ZNR Can be used for both 100V Varistor R AC and DC circuits.
2 ds_62003_en_micro_switches_technical_information: 010314J TECHNICAL TERMINOLOGY & CAUTIONS FOR USE Mounting state and environment 1. Checking the insulation distance snap action switches). This causes problems such as sticking of After mounting and wiring, check the 4) The perpendicular operating speed movable parts or operational time lags. insulation distance between terminals exceeds the allowable operating speed. 4) Low temperature, low humidity and the ground. If the insulation distance 5) Switching between different poles. environments is inadequate, mount insulating material 6) Use in environments not in the The plastic becomes brittle if the switch is between as required. prescribed temperature or humidity exposed to a low temperature, low 2. Fastening the snap-action switch range. humidity environment for long periods of body 7. Storage precautions time. See the Section “NOTES” for the To prevent discoloration due to 5) Storage for extended periods of time individual switch. sulfurization of the terminals (silver- (including transportation periods) at high 3. Position adjustment with effector plated), store the switches in a temperatures or high humidity levels or in The effector should be positioned so that polyethylene bag or other suitable airtight atmospheres with organic gases or direct force is not applied to the push- container. sulfide gases may cause a sulfide film or button or actuator in its free position. The 8. Usage, storage, and transport oxide film to form on the surfaces of the operating force to the push-button should conditions contacts and/or it may interfere with the only be applied in a perpendicular 1) During usage, storage, or functions. Check out the atmosphere in direction. transportation, avoid locations subject to which the units are to be stored and 4. Soldering precautions direct sunlight and maintain normal transported. 1) For manual soldering, lay the terminals temperature, humidity, and pressure 6) In terms of the packing format used, flat (horizontal with the ground) and conditions. The allowable specifications make every effort to keep the effects of quickly perform the soldering operation for environments suitable for usage, moisture, organic gases and sulfide using a soldering iron with the storage, and transportation are given gases to the absolute minimum. appropriate heat capacity and the proper below. 9. We reserve the right to modify amount of solder. Take care that the flux • Temperature: The allowable without notice the materials, internal does not flow into the switch interior by temperature range differs for each components, and other parts to using a ventilation fan to discharge flux switch, so refer to the switch’s individual improve product quality. gas and to prevent contact of the switch specifications. In addition, when 10. Handling precautions body with the soldering iron tip. Be transporting or storing switches while When handling the switches, be careful careful not to apply force to the lead wires they are tube packaged, there are cases not to drop them on the floor since this or the terminal portions immediately after when the temperature may differ from the may damage them. soldering. allowable range. In this situation, be sure For items 5. and 6., select contact The temperature setting and time to consult the individual specifications. sulfurization (clipping) prevention conditions vary depending on the • Humidity: 5 to 85% R.H. products (FS and Au clad 2-layer product. See the Section “NOTES” for contacts) for use with extremely small Humidity, %R.H. each product. loads or an environment-resistant 2) For automatic soldering also, see the Turquoise switch. 85 Section “NOTES” for each product. 11. Others Tolerance range 1) Failure modes of switches include
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