TR-7 Safe-T-Ground provides continuous
monitoring of a truck's ground connection throughout loading
operations. Static electricity is often brought in by tank trucks
entering the loading area. The Safe-T-Ground Model TR-7 instantly
stops loading operations if a tank truck loses its ground. The
simple but rugged Model TR-7 circuit continuously measures resistance
through the truck by applying a small voltage to one terminal
of the truck grounding contactor. The other terminal is connected
to the loading rack ground. If the Safe-T-Ground detects a resistance
of more than a few ohms across the contact terminals, the relay
opens, breaking the control circuit. The relay will not close
until the grounding contactor is properly connected.
To safeguard loading operations, the Safe-T-Ground circuit can
be wired into your pump control - and to an audible alarm or
The double wire TR-7 system provides an extra safeguard against
explosion, compared to single wire grounding, which cannot measure
the quality of the electrical ground connection durring loading.
The transistorized TR-7 circiut generates little heat - an added
The Model TR-7 Safe-T-Ground is simple and easy to install.
Removal of the cover on the explosion-proof aluminum housing
reveals the easily accessable terminal strip for relay and ground
control wiring, and a complete schematic wiring diagram appears
on a label next to the terminal strip for easy wiring. Coiled
grounding cable/contactor-handle assembly is easily replaced
via mil-spec connector on housing.