PC 200 Touch Switch
A capacitive device designed to initiate control operations when a metal antenna is touched.
Antenna size and shape are determined by the application; an antenna may be up to 200 feet long or have an area of 15 square feet. Adequate sensitivity is provided to insure operation if the antenna is covered with paint, oil, or dirt or if thin gloves are worn.
Principles of Operation
The PC200 Touch Switch system is comprised of: a control unit, and a customer-supplied antenna.
The Touch Switch is an electronic device which is sensitive to changes in capacitance. When a person’s body or a grounded metal object comes into contact with the antenna, a large change in capacitance results. Because it is capacitance, rather than electrical conductivity which is sensed, it isn’t necessary to make what is commonly thought of as an electrical connection with the antenna; therefore, the antenna may be covered with paint, electrical tape, or other thin insulating material and still function normally.
When sufficient external capacitance change is introduced, the internal signal voltage drops below a preset threshold level and causes the control relay to open. For speed purposes, the normal state of the relay is energized (closed contacts). This provides a faster response time and security against relay failure – if the relay coil fails, the control contacts open.
The Touch Switch is designed to tune a wide range of antenna capacity (0-1000pF). This gives the user plenty of latitude in application and doesn’t confine the touch surface to a small size or area. This makes the application possibilities for the Touch Switch virtually limitless.
- Conveyor Line Control
- Level Detector
- Machine Stop
- Parts Detector
- Limit Switch
- Easily Installed by Plant Electrician
- Complete Access and Visibility at Point of Operation
- Antennas are Application-Specific and can be Any Shape or Configuration
- Antennas Can Be Metal Rod, Pipe, Tubing or Flat Stock, Mounted on Insulators
- Low Cost Permits Installation at Each Location Where a Control Switch Need Exists
| Input Voltage | 115 VAC; +/- 15% | Control Contact | normally closed |
| Power Consumption | 4 VA | Indicators and Controls | indicator: one bi-color LED – green in reset, red in alarm |
| tuning: internal; one fine and one coarse potentiometer | |||
| System Reaction | 7.5mS | Enclosure
| NEMA4, industrial plastic 4.33 inches x 4.33 inches x 2.6 inches (110mm X 110mm X 66mm) |
| Antenna Size | up to 200 linear feet (60m) or 1000 pF of capacitance | Mounting | vertical or horizontal – to any bulkhead, chassis or panel |
| Sensitivity Range | touch activated | Weight | 1 lb. (.5 Kg) |
| Control Relay Load Rating | resistive: 2.5A, 15 VAC | Environment | unaffected by dirt, grease, vibration, etc. |
| inductive: 0.25A, 115VAC | temperature: 0° F – 130° F | ||
| humidity: 0 – 95% R.H. |
Safety Note
This overview is meant to illustrate some basic principles of antenna design – it is not intended to act as a substitute for the detailed instructions contained in the PC200 User’s Manual.
Please read the manual carefully before attempting an actual installation.
Antenna Definition
A rigid conductor, mounted on insulators and placed around or adjacent to an area to be protected. See the PC200 conveyor-stop application, for an example of a typical antenna.
Materials
Antennas may be constructed of metal rod, flat stock, 1/2″ or 3/4″ copper pipe or 3/4″ electrical conduit; materials must be rugged enough for the environment and hollow, in order to maximize field.
Insulators
Any rigid, nonporous insulating material is suitable to isolate the antenna from ground. The antenna must not touch ground, and should be kept 3 inches or more from grounded metal, if possible. Insulators should be wiped clean regularly, to insure proper operation. The insulators page gives prices and specifications on some insulators that are commonly used. These items may be purchased directly from Gordon, purchased from a plumbing supply or made by you.
Sensing Field
The unit generates an electromagnetic field around the antenna elements. This field is sensitive to touch by personnel, machinery and metal parts. Changes in the field are introduced when the antenna is touched, and the unit alarms.
Summary
- The antenna must be rigidly mounted to prevent movement relative to the machine and ground.
- The antenna must be isolated from ground.
- The antenna should be mounted no closer to ground than 3 inches.
- Install and test according to the PC200 manual.
| Pipe Clamps (mating pair) for ¾” Heavy-Wall Conduit | 02A050 Specifications |
| Pipe Clamps (mating pair) for ¾” EMT or Copper Tubing | 02A080 Specifications
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Conveyor-Stop Application
The antenna may be any shape, up to 200′ in length (1000 pF) and constructed of any rigid, conductive material – most often, electrical conduit, copper tubing or flat stock is used. A light touch, even with a thinly gloved hand, stops the conveyor.
The antenna is illustrated in yellow and insulators in blue.
