PC1000 Proxagard® System

Gordon PC1000 Proxagard SystemA Flexible RF Guarding System

A capacitive, presence sensing device designed for machine guarding and personnel safety applications.

Features microprocessor-based electronics, automatic tuning and sensitivity adjustments, continuous self-check circuitry, warning output, enhanced relay protection (includes welded contact detection), and ability to handle up to 150 linear feet of antenna.

Principles of Operation

The PC1000 Proxagard® system components are: a control unit, a coupler, and a customer-supplied antenna.

The control unit interfaces electrically with the coupler, by means of the coupler cable. The coupler is electrically and mechanically connected to the antenna, which is constructed near or around the area to be guarded.

The coupler generates an electromagnetic field which surrounds the antenna. Any intrusion into the field by personnel, machinery or metal parts causes a change in the field. The control unit detects this change and opens the control relay in the Stop Output circuit, which can be used to remove power, apply a brake or perform some other desired safety function. The Stop Output also has a safety relay, with its contacts wired in series with those of the control relay. The safety relay works in conjunction with an armature configuration in the control relay that allows a welded relay contact to be detected, and opens the Stop Output if a contact weld occurs. A separate, adjustable Warning Output provides a means to alert personnel to the fact that they are in the sensing field – this feature helps to eliminate unintended machine stops.

On initial power-up, the Proxagard® tunes automatically with the system sensitivity defaulted to maximum. The keypad allows the authorized user to retune and alter the sensitivity or warning settings; these new settings are stored in memory and become the defaults for subsequent power-ups. An access code prevents unauthorized keypad entry. The keylock is needed to allow the access code to be entered.  It becomes a second level of security to reduce operator adjustments to the system. The alarm point and field activity are displayed on a bar graph, during normal operation.

The self-check circuit, which monitors the control circuitry, operates continuously and is independent of machine cycle. In the event of a self-check fault, the Stop Output opens and a fault code is displayed on the bar graph.

Meets OSHA Standard 1910.217 (c) (3) (iii)

  • Machine Guarding
  • Safety Interlock
  • Machine Stop
  • Parts Detector
  • Warning Alarm
  • 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
  • Cost-effective guarding solution for complex machines or irregularly shaped areas
Input Voltage115 or 230 VAC, selectable; single
phase; 50/60 Hz; +/- 15%


epoxy encapsulated – impervious to water, dirt & oil
Power Consumption8 VACoupler Power Out1mW maximum
Frequency Range160 kHz – 400 kHzCoupler Cable10 feet (3m) standard – longer
lengths available
System Reaction25 mSIndicators and Controlsmode indicators: self-check, run, tune, set alarm and antenna fault alarm light
Self-Checkcontinuous, independent of machine cyclebargraph: displays alarm point and sensing field
Antenna Sizeup to 150 linear feet (45m) or 750 pF of capacitancekeypad: reset, tune, set alarm and set warning, with access code
keylock: prevents unauthorized changes of settings
Sensitivity Rangeup to 28 inches (711 mm) radius from antenna depends on antenna design


Enclosure Dimensions

NEMA 12, industrial plastic

10.2 inches x 6.1 inches x 4.0 inches

(259mm x 154mm x 102mm)

Stop Output Load Ratingresistive2.5A, 115 VACMountingvertical or horizontal – to any bulkhead, chassis or panel
resistive1.25A, 230 VAC
inductive.25A, 115 VAC
inductive.125A, 230 VAC
Stop Output Contactnormally closed, safety rated relayWeight6 lbs. (2.7 Kg)
Warning Output Load Rating8A, 115/230 VACEnvironmentunaffected by dirt, grease, vibration, etc.
Warning Output Contactnormally opentemperature: 0° F – 130° F

C-UL, US Listedhumidity: 0 – 95% R. H.
ListingsTested to UL 508 & CSA C22.2 No 14-95

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 PC1000 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 PC1000 automatic assembly application below for an example of a typical antenna.

PC1000 Automatic Assembly Application

The flexibility of the Proxagard® antenna system enables the safety engineer to design a sensing field which guards all pinch points. The antenna can be constructed to provide full visibility and access to any area of the machine, and may be up to 150 feet in length. The Proxagard® executes a control function (usually a machine-stop) when someone enters the field.

Antenna Elements are Yellow and Insulators are Blue

Mounting Distance – OSHA Regulation 1910.217(c)(3)(iii)(e) defines the Minimum Safety Distance for mounting an antenna by the formula below.

Formula for Calculating Minimum Safety Distance
Ds = K(Ts + Tp)Ds = Minimum safety distance between antenna and point of operation
K = 63/second (1.6 m/s)
Ts = Total stopping time of the electromechanical system
Tp = Total response time of the Proxagard® (0.025 seconds)

Example: If the mechanical stop time of a machine is 0.3 seconds, then the minimum safety distance for mounting the PC1000 Proxagard® antenna is 20.475″ [20.4785″ = (63″/s)(0.3s + 0.025s)]

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 4″ or more from grounded metal, if possible. Insulators should be wiped clean regularly, to insure proper operation. See the Mounting Clamps tab for 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 coupler generates an electromagnetic field around the antenna elements. This field is sensitive to personnel, machinery and metal parts. Changes in the field are detected by the Proxagard® and acted upon when the preset alarm levels are exceeded.

Field Shape Around a Tubular Antenna Element

This cross-sectional view of a sensing field around an antenna element depicts the effective field at the maximum and minimum alarm point settings.

In all illustrations in this section, green is used to depict the sensing field.

Field Shape around a Tubular Antenna Element

If a single antenna element is not sufficient to guard the area, two antenna elements may be placed parallel to one another 12″ to 24″ apart, which creates a strengthened field between them. When the optimum design and alarm point settings are achieved, the field between the elements is oblong, with no “holes” and very little peripheral sensitivity.

At the maximum setting the field may become bulbous and extend more than a desirable distance from the antenna. At the minimum alarm setting “holes” can develop in the protective field. If the unit’s alarm setting is at maximum and a “hole” still exists in the protective field, the antennal elements must be moved closer together or an additional element must be added.

Optimum Field Adjustment Between Parallel Antenna Elements
Optimum Field Adjustment between Parallel Antenna ElementsThere are no “holes” in the field and there is very little peripheral field sensitivity.

Grounded Shields – Another way to shape the sensing field is to construct grounded shields adjacent to the sections of the
antenna where an attenuation of sensitivity is required.

Shields can be made of any rigid, conductive material that is electrically isolated from the antenna and is grounded to the control unit’s electrical ground.

Grounded shields can be employed to shape the sensing field away from an operator’s workstation or the travel path of a machine component. The field will not extend past the shield, and will be diminished on the antenna side relative to the size and proximity of the shield. The closer the shield is to the antenna element the greater the amount of attenuation.

Effects of Ground Proximity on the Sensing Field
Ground ProximityGrounded Machine and Modified Antenna
Safety Note: It is extremely important that the shield and antenna be rigidly mounted and unable to move in relation to each other or the machine. Failure to observe these design rules can cause a hazardous condition,nuisance alarms, or both.

This principle of proximity to ground and attenuation of field sensitivity is also applicable to any metal machine parts which encroach on the antenna. It is possible for the attenuation to be severe enough to open “holes” in the protective field. One way to counteract this effect is to place an additional antenna element to reinforce the field in this location. Whenever possible, the preferred solution is to shape the antenna away from ground by at least 4″, as ground proximity decreases overall system sensitivity.

Planar Field Antenna – The Planar Field Antenna is a design which employs the principles of reinforcing fields and shielding to provide a flat sensing field with no lateral sensitivity and immunity to crosstalk from other Proxagard® antennas in the vicinity.

This configuration is ideally suited to single point of entry applications where the operator’s controls are in close proximity to the antenna. A concentrated zone of protection is provided and unintended alarms by operators or machine movement are avoided by virtue of the shielding.

Planar Field Antenna


  • The antenna and any shields must be rigidly mounted to prevent movement relative to each other, the machine and ground.
  • The antenna must be isolated from ground.
  • The antenna should be mounted no closer than the derived Minimum Safety Distance, and at least 3 inches up from the base of the machine.
  • Moving parts should not have excessive influence on the antenna, if they do shielding may be required.
  • The space between parallel antenna elements must be filled with field, to insure protection.
  • Install and test according to the PC1000 manual.

Guarding Automatic Assembly Machines

The flexibility of the Proxagard® antenna system enables the safety engineer to design a sensing field which guards all pinch points. The antenna can be constructed to provide full visibility and access to any area of the machine, and may be up to 150 feet in length. The Proxagard® executes a control function (usually a machine-stop) when someone enters the field.

Antenna Elements are Yellow and Insulators are Blue

Guarding Automatic Packaging Machines

The PC1000 Proxagard is ideally suited to guarding machines such as this one, which is a box making machine. Operators need access to most areas of the machine for set up and adjustment.

The Proxagard provides the guarding necessary, but also allows access to the machine without having to remove cumbersome mechanical guards or gates.

Guarding an Automatic Packaging Machine

Guarding Application Photo

Here a PC 1000 Proxagard System is shown perimeter guarding an automated assembly machine. The antenna and coupler are seen at the front of the picture.

This customer had the antenna installed and the Proxagard system up and running in less than four hours.

Machine Guarding for Automatic Assembly Machines

Mounting Clamps for the PC1000


Mount Clamps for PC1000 Proxagard


ApplicationGordon Part #LengthHoles (c-c)WidthHeightRadius
1/2″ Heavy Wall Conduit02A6931.961.291.180.700.42
1/2″ EMT02A6941.651.021.180.640.35
1/2″ Copper Tubing02A6861.651.021.180.640.32
1/2″ Diameter Stock02A6961.651.021.180.640.25
3/4″ Heavy Wall Conduit02A0502.321.571.180.820.53
3/4″ EMT02A6951.961.291.180.700.47
3/4″ Copper Tubing02A0801.961.291.180.700.44
3/4″ Diameter Stock02A6971.961.291.180.700.37


All Dimensions Are In Inches

All clamps are supplied in pairs.

The PC1000 Proxagard® will be repaired or replaced, for five years from the date of purchase, if it fails to perform to published specifications. The product must be used in accordance with the specified manufacturer’s ratings and must not be physically abused.