Shenhai Explosion-Proof
Connections Must Be Robust and Dependable
1. For conductive bolt-nut compression connections:
Utilize copper washers with the nuts. Wires can be crimped to O-ring connectors or prepared by stripping, coiling, tinning, and flattening for use as connectors. Ensure no stray strands protrude post-connection to minimize electrical gaps and creepage distance. When employing hex nuts and O-ring connectors, adjust distances G1 and G2 as depicted in Figure 7.11, ensuring compliance with required electrical gap standards.
Avoid U-type connectors for conductor connections due to the risk of detachment and spark generation upon loosening. Instead, use O-type connectors, which, even if loosened, increase temperature without separation. Any loosening of connections is strictly prohibited.
For wire bolt-nut crimping with low voltage and high current, fine-thread bolts and nuts are recommended.
2. For plug-in connections:
Implement a locking feature to secure the connection and prevent wire withdrawal. When using terminal plug-ins, secure the inserted wire core with a spring washer to ensure stability, as relying only on the terminal strip’s insulating material for friction is insufficient. Terminal strips lacking effective anti-loosening measures should not be used in explosion-proof electrical devices.
3. For welding:
Prevent any occurrence of ‘cold welding’ during the process, as it can compromise electrical circuit performance and increase weld point temperatures.
2. Wire Connections in Intrinsically Safe Circuits
1. Basic intrinsically safe circuit connections:
Besides ensuring connection reliability, they should typically be double-wired. When employing double-wire connectors, the connectors themselves must also support double-wiring.
This is considered a reliable method. As per the printed circuit board design, single-wire connections are permissible with a wire diameter of at least 0.5mm or a printed circuit width of at least 2mm.
2. Ground wires on printed circuit boards:
The ground wire should be broad and encircle the circuit board, maintaining a firm and dependable ground connection.