Garnet SeeLevel PosiGround 672-H Truck Grounding Controller

Chapter 1: Features and Operation

Congratulations on purchasing the Garnet Instruments Model 672-H SeeLevel PosiGround Truck Grounding Control System. The 672-H represents state-of-the-art truck-mounted grounding control systems, enhancing safety during the handling of flammable products by providing a positive indication of proper grounding.

The SeeLeveL PosiGround system comprises four main components: the controller (mounted inside or outside the truck cab), the PTO engagement or loading sensing switch, the grounding fault warning horn, and the ground connectors (clamp module, two ground cables, and two ground clamps).

SeeLeveL PosiGround System Overview

The PosiGround Controller acts as the system's 'brain', determining, displaying, and transmitting operational status and clamp connection integrity. It also manages the warning and final alarm outputs. The system is powered by the truck's 12V system, eliminating the need for batteries. The controller scans the grounding circuit and PTO input 16 times per second to assess system status.

Main Connector Electrical Connections:

• 12V Power: Connects to switched 12V truck power to operate the system. WARNING: All power circuits must be fused. An internal 10A fuse is present, but the wire to the controller requires a fuse with a maximum rating of 10 amps to prevent fires or electrical damage. This is the installer's responsibility.
• Ground: Connects to truck ground and the grounded grounding reel.
• Ground Sense: Connects to the insulated grounding reel and the clamp module.
• PTO Input: Connects to the PTO or engagement sensor to determine truck status. Programmable for various inputs (refer to Chapter 4 for "To program the engagement sensor pullup" and "To program the engagement sensor polarity").
• Warning Alarm Low Output: Provides ground connection to the warning device's ground side. The power side of the device must connect to 12V truck power.
• Warning Alarm High Output: Provides 12V power to the warning device's power side. The ground side connects to ground. (Not provided at this time).
• Final Alarm Low Output: Provides ground connection to the device's ground side. The power side must connect to 12V truck power. (Not provided at this time).
• Final Alarm High Output: Provides 12V power to the warning device's power side. The ground side connects to ground.

The system offers both "provides ground" and "provides 12V power" connections to accommodate different alarm/shutdown devices. Typically, only one connection is used. For devices that ground one side when mounted (like some horns or lights), the "provides 12V power" connection is used. All alarm outputs are internally protected against short circuits and voltage spikes.

Controller Display and Status Indicators

The controller features two reflective, backlit LCD displays visible in all lighting conditions. The top display shows the ground connection resistance, while the bottom display indicates truck grounding status (left) and PTO status (right).

Resistance Ranges:

• 250-ohm High Range: Measures resistance between 50 and 1000 ohms. Resistance less than 250 ohms is considered a good ground; greater than 250 ohms is an open circuit. Displays "999" for >1000 ohms and "u 50" for <50 ohms.
• 10-ohm Low Range: Measures resistance between 1.0 and 99.9 ohms. Resistance less than 10.0 ohms is a good ground; greater than 10.0 ohms is an open circuit. Displays "99.9" for >99.9 ohms and "u 1.0" for <1.0 ohms.

Bottom Display Status Conditions:

• Loading Disengaged (d): PTO or loading signal is disengaged. Warning horn is off, final alarm is disabled, allowing the truck engine to run. Grounding connection is shown on the left side.
• Loading Engaged (E): PTO or loading signal is engaged. Controls warning horn and final alarm outputs based on grounding connection status.
• Open Circuit (OP): Ground resistance exceeds the set limit (10 or 250 ohms). Indicates the truck is not grounded. If loading is engaged, a warning alarm activates for a set time, followed by a final alarm.
• Short Circuit (SH): Electrical connection between the ground sense line and ground, bypassing the clamp module. Indicates a short circuit in the grounding cables. If loading is engaged, a warning alarm activates, followed by a final alarm.
• Reversed Clamp Module (rE): Electrical connection between the ground sense line and ground is reversed. If loading is engaged, a warning alarm activates, followed by a final alarm.
• Good Ground Connection (GO): Ground resistance is within limits, and no short circuit or reversed clamp module is detected. Truck is properly grounded. Warning and final alarms are inactive.

Controller Front Panel Description: The front panel displays the Garnet logo, model number (MODEL 672-H), ground resistance (e.g., "1.0"), ground status indicators (OP, GO, SH, rE), and PTO status indicators (E, d). It also shows "GROUND RESISTANCE (OHMS)" and "GROUND STATUS PTO" labels.

Chapter 2: Clamp Placement Guidelines

Principle of grounding verification using the PosiGround:

A significant hazard when pumping liquids or granular solids is the buildup of electrical charge on the truck due to product movement. If this charge becomes high enough, an electrical spark can ignite a fire or cause an explosion. Grounding the truck continuously bleeds off this charge, preventing dangerous levels.

Proper grounding ensures the truck is electrically connected to the source location of the material being pumped (e.g., a tank or the ground itself for vacuumed materials).

The PosiGround verifies grounding by sending a small signal between clamps. Proper conduction of this signal indicates a good ground. Accurate results depend on correctly connecting the two clamps. The PosiGround is highly effective at verifying ground, surpassing reliance on visual inspection of a single cable.

For verification, PosiGround clamps must be connected to force the signal through the ground path. If pumping to or from a metal tank, clamps connect to force the signal through the tank wall. If a designated ground connection is provided, clamps connect to force the signal through the metal of the ground terminal.

It is never sufficient to have conductivity between clamps if the PosiGround signal does not travel through the intended ground path.

Good Grounding Situations:

• Good Situation #1: Truck with clamps connected to a ground rod and the material being pumped, separated by a significant distance (e.g., 20 feet). This ensures good underground conductivity, preventing significant voltage buildup on the truck from the moving material, thus avoiding sparks that could cause fire or explosion. The conductivity drains off developed voltage.
• Good Situation #2: Truck with clamps connected to underground pipes. The pipes may be close together but not connected, or they may head in different directions, ending far apart. This setup ensures the signal travels through the ground.
• Good Situation #3: Truck with clamps connected to ground rods that are close together (e.g., 5 feet apart) but situated within the material being pumped, ensuring depth.
• Good Situation #4: Pumping from a metal tank. Clamps are connected to two separate fittings, pipes, or brackets on the tank wall to ensure the signal travels through the tank wall.
• Good Situation #5: Truck connected to a ground rod or metal post, and a plastic tank connected via a ground rod or metal post to an earthen berm. Do NOT drive a ground rod inside the berm unless the containment area is verified to NOT have a liner.
• Good Situation #6: Truck connected to a provided ground spot (labeled as such) and another metal spot close by. This verifies clamp contact with the ground spot. DO NOT allow the clamps to touch each other!
• Good Situation #7: Truck connected to underground pipes via metal brackets or fittings. The pipes are connected but insulated for cathodic protection. The clamps are attached to separate points on the pipe system.

Bad Grounding Situations:

• Extremely Bad Situation #1 (Never do this!): Clamps are hooked together and lying on the ground. This truck is not grounded.
• Extremely Bad Situation #2: Truck is connected to a metal structure that is not grounded, and this structure is sitting on dry pavement or concrete. The truck is connected to the structure, but the structure itself is not grounded.
• Extremely Bad Situation #3: Clamps are connected to a valve instead of the pipes. The valve is isolated from the pipes by cathodic protection insulators at both flanges. This prevents the signal from traveling through the intended ground path.
• Bad Situation #1: Ground rods are too close together, and the area around them has poor conductivity (dry soil or gravel/sand). Local conductivity might appear good, but there is poor ground between the rods and the material being pumped.
• Bad Situation #2: Clamps are connected to pipes, but the pipes may be insulated (coated) from the ground. The PosiGround signal is not forced to travel through the ground, preventing proper verification of ground conductivity. Flanges are connected electrically, but the overall path is compromised.
• Bad Situation #3: Clamps are connected to a coated underground pipe. While connected to the pipe, if the pipe is insulated or coated, it may not be properly grounded.

Chapter 3: Operational Procedures

1. When the operator is ready to handle, load, or unload flammable material, the truck must be grounded.
2. Connect one clamp to a metal object that appears grounded, and the other clamp to another metal object at least 20 feet away that also appears grounded. Ideally, both objects should have a buried portion. Refer to Chapter 2 for "Clamp Placement Guidelines".
3. Check the display: it should show "GO d", indicating a good ground with loading or unloading not yet started. The actual ground resistance in ohms can be noted from the top display.
4. Loading or unloading can commence. If loading is attempted before grounding, the warning horn sounds for a set time, followed by a final alarm unless the ground connection is made within the set time.
5. If the ground connection is lost during loading, the warning horn sounds for a set time, and the final alarm activates unless the connection is re-established within the set time.
6. When loading is complete, shut down the loading system and disconnect the grounds.
7. If the ground is lost and the warning horn is sounding, shutting down the loading system will silence the horn.
8. If the PosiGround displays "SH" or "rE" with cables connected, there is a defect in the ground cable wiring that must be corrected before use.
9. Each time a proper grounding connection is established or the loading system is shut down, the timer resets.
10. The PosiGround system requires periodic testing to ensure the warning horn and final alarm activate correctly. New operators must also be tested to confirm familiarity with PosiGround operation for their specific vehicle.

Important Safety Warnings:

• ⚠️ WARNING: The PosiGround is an emergency backup system only and not a substitute for operator diligence during loading/unloading.
• ⚠️ WARNING: Operators must properly connect ground cables for correct PosiGround operation. Hooking clamps together and placing them on the ground does NOT constitute a proper ground connection.
• ⚠️ WARNING: Do NOT travel with ground clamps hooked together or the ground sense clamp connected to the truck frame. This can lead to operators forgetting to connect clamps properly, as no warning will be given at the start of loading/unloading.
• ⚠️ WARNING: Installers must properly connect and test warning horn and final alarm features. If systems are not fully connected, the truck operator must be informed of the PosiGround's capabilities.

IMPORTANT SYSTEM OVERRIDE

In the event of a PosiGround system failure causing truck shutdown, the dash-mounted PosiGround switch can be set to OVERRIDE from NORMAL. This position disables the engine shutdown feature, though other features like the warning horn may remain functional.

• ⚠️ WARNING: When the PosiGround switch is in OVERRIDE, engine shutdown is disabled, and grounding protection is eliminated.

Chapter 4: Programming Instructions

The PosiGround has seven programmable options, adjusted using two buttons on the back of the display panel.

To Program Warning Horn Delay Before Final Alarm:

1. Hold the SELECT button until "HndE" appears on the top display, then release.
2. Press SET repeatedly to set the desired delay. Increments are 2 seconds (under 10s), 5 seconds (10-30s), and 10 seconds (30-60s). Pressing SET after 60s resets to 0.
3. Press SELECT to cycle through options. "donE" appears when done. The system returns to normal operation upon release. A 5-minute inactivity timeout also returns the system to normal. To stay in programming mode, press SET while holding SELECT at "donE".

To Program Warning Horn Sound (Steady or Oscillating):

The horn can sound steady or oscillate every second. Oscillating is more attention-grabbing, but some sounders already oscillate.

1. Hold SELECT until "HndE" appears, then release.
2. Press SELECT again until "Horn" appears on the top display and "StEd" or "OSCL" on the bottom.
3. Press SET to toggle between steady ("StEd") and oscillating ("OSCL").
4. Press SELECT to cycle through remaining options. "donE" appears when done. The system returns to normal operation upon release or after 5 minutes of inactivity. To stay in programming mode, press SET while holding SELECT at "donE".

To Program Warning Horn Behavior (On/Off After Expiry):

The horn warning can be set to turn off after the warning time expires or to remain on indefinitely.

1. Hold SELECT until "HndE" appears, then release.
2. Press SELECT again until "Horn" appears on the top display and "On" or "Off" on the bottom.
3. Press SET to toggle between "On" (stays on) and "Off" (turns off).
4. Press SELECT to cycle through remaining options. "donE" appears when done. The system returns to normal operation upon release or after 5 minutes of inactivity. To stay in programming mode, press SET while holding SELECT at "donE".

To Program the Final Alarm:

The final alarm activates after the warning horn times out when ground is lost. This output can be programmed for an open or closed circuit.

1. Hold SELECT until "HndE" appears, then release.
2. Press SELECT again until "FinL" appears on the top display.
3. Press SET to change the mode between open circuit ("OPEn") and closed circuit ("CLOS").
4. Press SELECT to cycle through remaining options. "donE" appears when done. The system returns to normal operation upon release or after 5 minutes of inactivity. To stay in programming mode, press SET while holding SELECT at "donE".

To Program the Range:

The PosiGround can determine grounding status at 250 ohms (high range) or 10 ohms (low range).

• High Range (250 ohms): Typically used for grounding through earth, between ground rods, or unconnected metal structures. Specifications often require resistance less than 1000 ohms; 250 ohms is used as the decision point for margin.
• Low Range (10 ohms): Used for grounding to metal structures that are themselves properly grounded, common at loading facilities. Specifications usually require metal-to-metal resistance less than 10 ohms.

The operator or installer determines the appropriate range.

1. Hold SELECT until "HndE" appears, then release.
2. Press SELECT again until "rAng" appears on the top display.
3. Press SET to change the range between 10 ohms ("r10") and 250 ohms ("r250").
4. Press SELECT to cycle through remaining options. "donE" appears when done. The system returns to normal operation upon release or after 5 minutes of inactivity. To stay in programming mode, press SET while holding SELECT at "donE".

To Program the Engagement Sensor Pullup:

This setting is for indicating engagement. If the signal is a switch connected only to ground, the pullup must be ON to detect it. If the signal is connected to 12 volts or a light bulb, the pullup is not needed.

1. Hold SELECT until "HndE" appears, then release.
2. Press SELECT again until "PtoP" appears on the top display.
3. Press SET to toggle pullup between "On" and "OFF".
4. Press SELECT to cycle through remaining options. "donE" appears when done. The system returns to normal operation upon release or after 5 minutes of inactivity. To stay in programming mode, press SET while holding SELECT at "donE".

To Program the Engagement Sensor Polarity:

This setting indicates engagement. If the signal is ground for engagement, polarity should be set to ground. If the signal is 12 volts, polarity should be set to power.

1. Hold SELECT until "HndE" appears, then release.
2. Press SELECT again until "PtoE" appears on the top display.
3. Press SET to change polarity between ground ("GND") and 12V power ("12V").
4. The engagement sensor status on the bottom right display updates immediately to confirm the setting.
5. Press SELECT. "donE" appears when done. The system returns to normal operation upon release or after 5 minutes of inactivity. To stay in programming mode, press SET while holding SELECT at "donE".

To Check the Software Version:

During normal operation, press the SET button. While held, the display shows "672H" and the revision (e.g., "r1.09").

Chapter 5: Installation Guide

Refer to the wiring diagram in Section D during installation of the PosiGround system.

1. Mounting Location: Choose a spot for the controller box that is protected from kicks, tools, equipment, road wind, and spray. The face should be easily visible to the operator. The controller must be mounted on the same vehicle as the loading system it controls (e.g., if shutting down a truck engine driving a PTO pump, mount on the truck, not the trailer).
2. Enclosure Installation: Install wiring fittings into the enclosure and mount the display enclosure using the provided flange holes.
3. Pneumatic Switch Connection: If applicable, connect the pneumatic switch's pressure port to the appropriate sensing point for loading control. Contact Garnet if unsure about sensing loading activation.
4. Ground Cable and Clamp Installation: If the truck lacks an existing ground cable and clamp, install one. Mount a second cable and clamp for the ground sense line. The first grounding reel must be mounted to a clean, conductive surface using its four base mounting holes. The second grounding reel (for ground sense) must be isolated, achievable with an isolation plate and shoulder washers (supplied). See wiring diagram on page 15.
5. Clamp Module Connection: Connect the clamp module between the ground sense cable end and the ground sense clamp. The RED wire from the module connects to the cable, and the BLACK wire connects to the clamp.
6. Wiring: Connect the controller's black GROUND wire to ground. Connect the controller's yellow GROUND SENSE wire to the ground sense cable. Refer to the wiring diagram.
7. 12V Power Connection: Connect the controller's red 12V DISPLAY LIGHT wire to a 12-volt ignition source to prevent truck battery drain when the engine is off.
8. Horn Connection: If applicable, connect the controller's orange HORN wire to an electrical warning horn. The controller completes a circuit to ground for the horn; one side of the horn needs 12V, and the other connects to the HORN wire.
9. Shutoff Switch Wiring: Locate an electrical shutoff switch for the loading system. Break its connection and attach the two wire ends to terminals (#30 and #87) of the auxiliary shut down (SD) relay (supplied). Connect one SD relay coil terminal (#86) to a 12V ignition source and the other (#85) to the green SHUTDOWN wire from the PosiGround controller. Mount the ESD relay near the shutoff wiring to minimize wire length.
10. PTO Sense Wire: Connect the controller's purple PTO loading sense wire as required.
11. Controller Programming: Program the controller for required functions per the programming section.
12. Emergency Bypass Switch: If the PosiGround is set to shut down the truck engine, connect an emergency bypass switch across the auxiliary SD relay terminals for emergency starting in case of system failure. Locate the switch where it cannot be accidentally activated and install a label indicating its position (available from Garnet).
13. System Testing: Test for proper operation (see Section B for procedures). If loading is shut down and clamps are disconnected, the PosiGround should show "OP d". Engaging loading should show "OP E" and activate the warning horn. After the warning time, the horn stops, and the final alarm activates. Connecting ground clamps should show "GO E", allowing loading to start. If the controller shows "rE E" or "SH E", the clamp module wiring is incorrect. MAKE SURE the horn warning and final alarm systems function correctly.
14. Unconnected Features: If the final alarm or warning horn features are not connected, MAKE SURE this is noted in the owner's manual, and the operator is aware of the system's limitations.

Chapter 6: Wiring Diagram

SeeLeveL PosiGround 672-H WIRING DIAGRAM

The diagram illustrates connections for FUSED 12V POWER, CLAMP MODULE, PRESS SWITCH, CABLE REELs, ISOLATION PLATE, WARNING HORN OR LIGHT, STROBE LIGHT, and the MAIN CONNECTOR. It details connections for GND SENSE (YELLOW), PTO SENSE (PURPLE), +12V (RED), GND (BLACK), WARN ALM HI (WHT/ORG), WARN ALM LO (WHT/BLU), FINAL ALM HI (GREY), FINAL ALM LO (GRN/YEL). It also shows connections for SER TX (WHT/PUR) and SER RX (WHT/YEL) to a PLC OR COMPUTER. A 10A FUSE is indicated. Notes specify using either HI or LO connection for alarms, not both.

Chapter 7: Troubleshooting Guide

The PosiGround system has three serviceable components: the controller, the clamp module, and the pneumatic switch. Each can be tested independently.

• Pneumatic Switch Test: Disconnect terminals and use a continuity tester. Continuity should exist with no pressure. Applying over 4 PSI of air pressure should open the switch.
• Clamp Module Test: Connect the red wire to the controller's yellow ground sense wire and the black wire to the controller's black ground wire (using a known good controller). The controller should display "GO". If not, the module is defective.
• Controller Test: Connect test lights between +12 volts and the warning horn/final alarm wires. Connect a known good clamp module (CM red to controller yellow, CM black to controller black). The display should read "GO E", the final alarm light should be ON, and the warning horn/light OFF. Allow 1-2 seconds for display response.
• Shorting ground sense and ground wires: Display should show "SH E". Final alarm light stays ON, warning horn/light flashes for a set time, then both go out.
• Shorting final alarm and ground wires: Final alarm light turns ON, display shows "SH d". Removing this short starts the warning horn/light flashing, and the final alarm light stays ON for a set time.
• Remove short between ground sense and ground wires: Display should read "GO E" again.
• Removing clamp module: Display should show "OP E". Final alarm light stays ON, warning horn/light flashes for a set time, then both go out.

If components check out but issues persist, inspect wiring for faults, starting from the controller.

Chapter 8: Specifications

CONTROLLER

• Material: Cast aluminum enclosure.
• Size: 226 mm (8 ⅞") wide, 143 mm (5 ⅝") high, 92 mm (3 ½") deep.
• Display type: Wide temperature LCDs, 4 digit, 7 segment with backlight.
• Display size: 12.7 mm (½") high digits.
• System power requirements: 12 V truck power required; current drain less than 20 mA (excluding alarm outputs).
• Accuracy: Ground resistance measurement accuracy is ±2% at switching points (10 or 250 ohms); ±5% at measurement extremes.
• Ambient temperature range: -40°C to +60°C (-40°F to +140°F).
• Alarm output ratings: Both alarm outputs can provide at least 2 amps to the load. Maximum voltage is 16 V. Outputs are internally protected from short circuits and voltage spikes.

SAFETY INFORMATION

• Compliance and Certifications: Complies with CAN ICES-001(A)/NMB-001(A) and FCC Rules Part 15. Operation is subject to conditions: no harmful interference, and acceptance of received interference. Changes not expressly approved may void user authority.
• Chemical Exposure: This product may expose users to Nickel and Lead, known in California to cause cancer and reproductive harm. More information at www.P65Warnings.ca.gov.

Chapter 9: Service and Warranty Information

For warranty claim process information, visit the support page at: www.garnetinstruments.com/support/

DISCLAIMER OF WARRANTY ON HARDWARE

Garnet Instruments warrants manufactured equipment to be free from defects in material and workmanship for one year from the date of sale. The warranty covers actual loss or damage up to Garnet's invoiced price. Garnet is not liable for labor charges, indirect, special, or consequential damages, nor for removal/reinstallation of defective equipment. Warranties do not apply to altered or tampered equipment or non-Garnet products used in unacceptable applications or outside technical specifications. Products must be installed and maintained per factory specifications.

LIMITATION ON WARRANTIES

These are the only express or implied warranties. Garnet disclaims warranties of merchantability or fitness for a particular purpose. Defective products should be returned to the seller, distributor, or Garnet for evaluation. For factory evaluation, service, or replacement, a Returned Material Authorization (RMA) from Garnet Instruments is required. Returns must be freight prepaid to Garnet Instruments, 286 Kaska Road, Sherwood Park, Alberta, T8A 4G7. Garnet will repair or replace warranted items at its discretion. Irreparable items will be replaced at no charge or credited.

For warranty claims or service, contact the installation dealer. For direct contact with Garnet:

• CANADA: Garnet Instruments, 286 Kaska Road, Sherwood Park, AB T8A 4G7. Email: info@garnetinstruments.com
• UNITED STATES: Garnet US Inc., 5360 Old Granbury Road, Granbury, TX 76049. Email: infous@garnetinstruments.com