STS 300 Static Ground Monitoring System

The STS 300 is a static ground monitoring system that continuously verifies a low-resistance path from the grounding clamp to a verified ground during material transfer. Two dry relay contacts interlock pumps, valves and alarms, so a transfer cannot start, or continue, without a confirmed ground. Special Technical Services, founded in 1976 and based in Budd Lake, NJ, builds the STS 300 in the USA in single-point and multipoint versions.

What the STS 300 does

A grounding clamp makes the physical connection, but it cannot tell the operator whether that connection is still electrically sound. The STS 300 uses an intrinsically safe monitoring circuit, a grounding cable and a clamp to check the path from the clamp to ground for the whole operation, against a resistance-to-ground setpoint of less than 5 ohms per NFPA 77.

• Continuous monitoring. The STS 300 checks the ground path from hookup to disconnect, not only at the start of the transfer.
• Automatic interlock. Two interlocking dry contacts connect to filling equipment and controls. If the system cannot verify a proper ground, the contacts change state and connected equipment is halted until the ground is re-established. Common integrations start or stop pumps, open or close valves, and sound alarms.
• Visual status. Indicator lamps show the grounding status at a glance: green when a proper ground connection is made, red when the circuit is broken or the ground is interrupted.

Indicator light status

See the full STS 300 page: configurations, specifications, applications and FAQs

The same reliability and features as the STS 300 with the convenience of simultaneous grounding of up to four pieces of equipment. The STS 300 Multipoint provides operators with a single control device and will only operate when all cables are successfully connected, to ensure multiple pieces of equipment are safely grounded. Ground cables are available in multiple types and lengths. In addition to green and red grounded indicators, the STS 300 Multipoint can also be utilized to turn equipment off if the ground is interrupted. This is an ideal and cost-effective solution for work areas that typically involve multiple pieces of equipment that are utilized at the same time.