A compact switch equipped with an enclosed micro-gap snap-action contact mechanism that makes a specified motion with a specified force to open/close a circuit, and an actuator outside the enclosure (hereinafter referred to as the switch)
A part of the switch that transmits the received external force to an internal spring mechanism to move the movable contact so that the switch can be opened and closed
A part of the switch to limit the actuator movement in the switch operation direction
Values indicating the characteristics and performance guarantee standards of the snap-action switches. The rated current and rated voltage, for instance, assume specific conditions (type of load, current, voltage, frequency, etc.).
The service life when operated at a preset operating frequency without passing electricity through the contacts. (The life test is performed at a switching frequency of 60 times/minute and operating speed of 100 mm/second at the regular cam.)
The service life when the rated load is connected to the contact and switching operations are performed. (The life test is performed at a switching frequency of 20 times/minute and operating speed of 100 mm/second at the regular cam.)
This refers to the components determining the type of application which make up the electrical input/output circuits in the contact.
Resistance between non-continuous terminals, each terminal and other exposed metal parts and between each terminal and ground.
Threshold limit value that a high voltage can be applied to a predetermined measuring location for one minute without causing damage to the insulation.
This indicates the electrical resistance at the contact part. Generally, this resistance includes the conductor resistance of the spring and terminal portions.
|Malfunction vibration||:||Vibration range where a closed contact does not open for longer than a specified time due to vibrations during use of the snap-action switches.|
|Shock durability||:||Shock range where the mechanical shocks received during snap-action switches transport and installation do not damage the parts or harm the operating characteristics.|
|Malfunction shock||:||Shock range where a closed contact does not open for longer than a specified time due to shocks during use of the snap-action switches.|
The main terminological illustrations and meanings which are used with snap-action switches are as follows.
|Classification||Terminology||Symbol||Unit||Varying display method||Starting current|
|Force||Operating Force||OF||N||Max.||The force required to cause contact snap-action. It is expressed terms of force applied to the the actuator.|
|Release Force||RF||N||Min.||The force to be applied to the the actuator at the moment contact snaps back from operated position to total travel position.|
|Totaltravel Force||TF||N||Force applied to an actuator required to move from an operating position to a total travel position|
|Movement||Pretravel||PT||mm, degree||Max.||Distance or agree of the actuator movement from free position to operating position.|
|Overtravel||OT||mm, degree||Min.||The distance or degree which the actuator is permitted to travel after actuation without any damage to the switching mechanism.|
|Movement Differential||MD||mm, degree||Max.||The distance or degree from operating position to release position of the actuator.|
|Totaltravel||TT||mm, degree||The migration length or the move angle from the free position to total travel position of actuator|
|Position||Free Position||FP||mm, degree||Position of the actuator when no force is applied to.|
|Operating Position||OP||mm, degree||±||The position of the actuator when the traveling contacts snaps with the fixed contact.|
|Release Position||RP||mm, degree||The position of the actuator when the traveling contact snaps back from operating position to its original position.|
|Totaltravel Position||TTP||mm, degree||The stopping position of the actuator after total travel.|
Adequate stroke setting is the key to high reliability.
It is also important that adequate contact force be ’maintained to ensure high reliability.
For a normally closed (NC) circuit, the driving mechanism should be set so that the actuator is normally in the free position.
For a normally open (NO) circuit, the actuator should be pressed to 70% to 100% of the specified stroke to absorb possible errors.
If the stroke is set too close to the operating point (OP), this may cause unstable contact, and in the worst case may cause actuator damage due to inertia of the drive mechanism. It is advisable that the stroke be adjusted with the mounting plate or driving mechanism.
The figure at right shows a typical example of activation and contact forces varying with stroke. In the vicinity of the OP and RP, the contact force is diminished, causing chatter and contact bounce immediately before or after reversal. For this reason, use the switch while giving due consideration to this. This also causes the snap action switch to be sensitive to vibration or shock.
Exercise design care so that malfunctions will not occur if the operating characteristics vary by as much as 20% from, rated values.
In the OF max. 0.98N specification for FS snap-action switches,
the allowable max. is 0.98 N × (100%+20%) = 1.18 N
In the RF min. 0.15 N min. specification
the allowable min. 0.15 N × (100%–20%) = 0.12 N
Actuator type should be selected according to activation method, activation speed, activation rate, and activation frequency.
Use of a driving mechanism which will cause physical impact to the actuator should be avoided.
|Circuit diagram||Cautions for use|
(1) r = more than 10 Ω
(2) In an AC circuit
|Can be used for both AC and DC.
Impedance of r is nearly equal to
impedance of R.
C: 0.1 μF
|(1) For DC circuits only.|
|Can be used for both AC and DC.|
After mounting and wiring, check the insulation distance between terminals and the ground. If the insulation distance is inadequate, mount insulating material between as required.
See the Section “Cautions for Use” for the individual switch.
|1.||When the switch is not pressed|
The object to press the lever should not be in contact with the lever.
For this purpose, the object should be at a distance from the switch father than the maximum FP (Free Position) value.
FP max = OP max + PT max = 9.6 + 2.8 = 12.4 mm max
The object should be at a distance of 12.4 mm or more from the mounting hole.
The plunger/lever should be pressed down to 70% or more of OT (Over Travel).
Therefore, the depressed position should be calculated based on the minimum value of
OP (Operating Position) and the 70 and 100% of the OT value.
OP min - 70% of OT = 8.0 - 0.84 = 7.16 mm
OP min - 100% of OT = 8.0 - 1.2 = 6.80 mm
The plunger/lever should be pressed down to the position of 6.80 to 7.16 mm from the mounting hole.
Avoid using organic silicon rubber, adhesives, sealing compounds, oil, grease, and wires in a silicon atmosphere.
To prevent discoloration due to sulfurization of the terminals (silver- plated), store the switches in a polyethylene bag or other suitable airtight container.
During usage, storage, or transportation, avoid locations subject to direct sunlight and maintain normal temperature, humidity, and pressure conditions.
The allowable specifications for environments suitable for usage, storage, and transportation are given below.
(The allowable temperature depends on the switch.)
When handling the switches, be careful not to drop them on the floor since this may damage them.
|*||Select contact sulfurization (clipping) prevention products (FS and Au-clad double layer contacts) for use with extremely small loads or an environment-resistant Turquoise switch.|
|Shape||Classification||Pretravel (PT)||Overtravel (OT)||Operating Force (OF)||Vibration
|Pin plunger||Small||Small||Large||Out-standing||Appropriate for linear short-stroke action. Pin plunger acts directly on snap action mechanism, enabling high-precision positioning. Amount of movement after operation is smallest among all of the actuators, however, so reliable stopper is required.|
Little force required for operation. Appropriate for use with low-speed cams and dogs; has large stroke.
Lever available in various shapes to fit operating unit.
|Large||Medium||Small||Possible||Tip of hinge lever is bent into a semi-circle, enabling use as a simple roller type.|
|Leaf lever||Large||Large||Small||Excellent||Play in lever is used to assure maximum stroke. Construction provides for space where lever is attached, for outstanding resistance to freezing.|
|Hinge roller lever||Large||Medium||Small||Possible||
This is a hinge lever with a roller, and can be used with high-speed cams and dogs.
The force required for pin plunger action is lighter than that of the lever, and the stroke is longer.
|ABJ (BJ) Turquoise Switches|
|Ultra-miniature Size Sealed Switches|
|ABS (BS) Turquoise Switches|
|Subminiature Size Sealed Switches|
|ABV (BV) Turquoise Switches|
|Miniature Size Sealed Switches|
|Turquoise Stroke Switches|
|Long Stroke and Sliding Contact Construction Sealed Switches|
|Turquoise Stroke Mini Switches|
|Long Stroke, Sliding Contact Construction Sealed Switches|