HCD sensor Precautions During Use

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About detection target size, material and coating

• Detection distances have been set for each model using a standard detection target of a specific size.
  The detection distances may decrease with smaller detection targets.
• The detection distance is unaffected by the plate composition, including whether or not the plate is plated.

About the operating environment

• Avoid using the sensors outdoor, in locations exposed to direct sunlight, or in locations where the temperature may vary rapidly and repeatedly. Otherwise, the internal parts and the case may deteriorate.
• Avoid using the sensors in locations where chemical, organic solvents, or other such materials may splatter.
• If the sensor is installed near devices generating large surges, such as motors, welding machines or solenoids, install a surge absorber to the surge generating device.
• When using a switched-mode power supply, always connect the FG terminal to the ground to prevent generation of harmonics.
• HCD sensors use high-frequency oscillation circuits.Therefore, the sensor may malfunction if high-frequency devices (welding machines, inverter-fed motors, broadcasting stations) are used near the sensor installation location. Always connect installed and surrounding metal objects to the ground.

About the wiring

• Always check that the wiring is correct before turning on the system as incorrect wiring may damage internal circuits.
• Use large-diameter cables when extending the cord to minimize voltage drop effects.
  Note that distortion may appear in the output waveform when using an extension cable depending on the line capacity.
• If the cables are installed parallel to high-voltage lines or power lines, malfunction or damage may result from induction noise. Therefore, separate the cables or install them into an independent metal raceway.

About the load used

A transistor is used for the sensor output.
Therefore, the transistor may deteriorate or be damaged if an inductive load generating large inrush current, such as a lamp or a motor, is switched.In such cases, use a relay or similar device.

About power supply of HCD sensor

(1)When power is supplied by a battery
Connect directly, or via a 1000 pF capacitor, the GND side (0 V) of the sensor power supply to the earth or to a large metal frame. Connect it fully without any poor contact.

(2)When the coupling capacitance is small between the primary and the secondary sides of the sensor power supply
When using a DC to DC converter, connect directly, or via a 1000 pF capacitor, the GND side (0 V) of the sensor power supply to the earth or to a large metal frame. Connect it fully without any poor contact.
If the above connection is not possible, connect it to the GND side of the primary-side DC power supply.

*Use a capacitor with sufficient withstand voltage.

According to its operating principles, the sensor detects the capacitance between the sensor electrode and ground. When a high-frequency voltage of several hundreds of kHz or higher (common mode noise) to ground is superimposed on the sensor power line, it will interfere with sensor operation, and the following malfunctions could result; higher detection sensitivity, detection stuck ON at all times, or deterioration of internal parts/components.

Typical sources of common mode noise are as follows (including wiring of each):
・Inverter devices (power supplies for inverter motors and pulse motors)
・Vibration generators
・Switching power supplies
・Wireless devices
・Microwave generators
・Large power transmission antennas

To avoid common mode noise generation in the sensor power line, connect the sensor ground (GND, 0V) either directly to ground, or to ground via a 1,000 pF or higher capacitor of sufficient withstand voltage, or else to the frame ground (F.G.) with sufficient capacitance to ground. When connecting the sensor to ground via the sensor housing, ensure correct electrical bonding to avoid contact resistance. Common mode noise has a large electrical field strength compared to differential noise (normal mode noise), being 100 times (100 MHz) to 10,000 times (1MHz) larger using the same current, cable loop area, and frequency conditions. Accordingly, a countermeasure of simply separating the line experiencing the common mode noise from the sensor wiring is insufficient and not recommended.To avoid common mode noise, use a shielded cable, or more effectively, adequate shield grounding should be used.

Mounting

• The detection distance varies depending on the target conductivity, permittivity, and volume. Therefore, check the detection distance in advance using the appropriate target, and set the distance taking into account an error margin. If one or several targets with small permittivity are placed or stacked on the detection surface, the reset operation may not work properly due to the quantity target objects. It is recommended to check that such problem does not occur before using the sensor.
• Note that the reset operation may not work properly if water adheres to the detection surface, or if condensation or frost is generated due to change in the temperature.

Interference due to high frequency emissions from surrounding devices

This touch switch is sensitive to high frequencies. To avoid interference by emissions from surrounding equipment. be sure to plan ahead.

Static Electricity

In the dry environment of the winter season, the human body generates static electricity of thousands or tens of thousands of volts, and is influenced by synthetic fibers or wool carpets.
If such a person then touches a touch electrode, a static discharge occurs.
All the static electricity discharged to the touch electrode is diverted to the GND line. Accordingly, the GND line needs to be as short as possible, or the impedance needs to be as small as possible.
This anti-static characteristic depends on the wiring condition and circuit connections. Please check by using the actual product in its intended environment.
It is more effective if the GND line is routed to the F.G. side via a capacitor.

Usage Environment

For both use and storage of the product, avoid any place which is exposed to water, oil, chemicals or corrosive gases,abrupt temperature changes, or direct sunlight. Dew condensation or icing could affect the proper characteristics of the product.