Complete Configuration of the Specialized Static Grounding Alarm for Railway Oil Unloading Trestles
Suitable for use at oil depots, railway trestles, road oil unloading platforms, and refueling trucks. Explosion-proof rating: Ex d II BT4. The system comprises five main components: the main control unit, the grounding clamp and cable assembly, the audible/visual alarm output, the circuit detection module, and explosion-proof accessories.
I. Explosion-proof Main Unit Assembly (Core Control Unit)
Explosion-proof Housing
Cast aluminum explosion-proof enclosure with flameproof structure; IP54 protection rating; features an internal sealing gasket for rain and dust resistance, suitable for outdoor trestle use.
Main Detection Circuit Board
Core resistance detection chip for real-time monitoring of grounding circuit continuity resistance; alarm threshold set to trigger at >10Ω and indicate normal status at <10Ω (compliant with aviation fuel specifications).
Power Supply Module
Two power supply options:
Built-in lithium battery: High-capacity explosion-proof battery allowing for months of continuous operation;
External 24V DC explosion-proof power supply: Compatible with trestle PLC systems.
Reset/Self-test Button
Explosion-proof tactile button for power-on self-test, fault reset, and simulated grounding test.
Terminal Wiring Chamber
Independent flameproof wiring compartment with cable sealing glands; two cable channels: one for the grounding clamp cable and one for the interlock output cable.
II. Grounding Detection Circuit Assembly (Connection to Tanker/Rail)
Heavy-duty Static Grounding Clamp
High-strength cast steel clamp body with a powerful spring;
Alloy steel piercing teeth designed to penetrate paint and rust layers on tanker trucks and rails, ensuring metal-to-metal contact;
Anti-detachment latch to prevent accidental loosening during operation.
Oil-resistant, Explosion-proof Connection Cable
Flexible multi-strand copper core cable with an outer sheath resistant to aviation kerosene; standard lengths of 5m, 8m, or 10m; reinforced with internal tensile fibers to prevent breakage during dragging.
Quick-connect Fitting
Waterproof, pluggable connector between the clamp body and the main unit, facilitating easy cable replacement and storage. III. Audible and Visual Alarm Output Unit
High-decibel explosion-proof buzzer (red)
Sounds continuously in the event of poor grounding, wire breakage, or excessive resistance; volume ≥90dB, ensuring audibility even in the noisy environment of the loading gantry.
Explosion-proof LED indicator
Steady green light: Grounding is compliant; oil unloading operations are permitted.
Flashing red light + buzzer: Grounding failure, circuit disconnection, or excessive resistance.
Some models feature a fault code display window for easy maintenance.
IV. Interlock Output Module (Essential for automated oil depot control)
Passive relay contacts (dry contacts)
Two sets of normally open/normally closed contacts; connectable to PLCs, unloading pump control cabinets, and pneumatic emergency shut-off valves.
Interlock logic:
Non-compliant grounding → Output interlock signal → Prevent unloading pump startup and close the unloading shut-off valve.
Grounding restored → Interlock automatically disengaged; oil transfer permitted.
Explosion-proof sealed interface for signal cables; connects to the local operation box on the loading gantry.
V. Supporting Accessories
Fixed mounting bracket
Stainless steel wall-mount bracket; mountable on gantry columns or loading arm pillars; includes vibration-dampening gaskets.
Cable reel (optional)
Compact spring-loaded reel for storing the grounding cable, preventing damage from dragging or crushing.
Grounding resistance calibration plug
Used for periodic accuracy checks of the alarm unit; simulates excessive resistance to verify proper alarm function.
Installation consumables: Explosion-proof cable glands, sealing gaskets, mounting bolts, etc.
Brief Operating Principle
Grounding clamp attaches to the tanker body → Current flows through the cable into the main unit's detection circuit → Real-time measurement of the conductive resistance between the vehicle and the earth.
Resistance <10Ω: Green light on, interlock circuit closed, unloading permitted.
Resistance >10Ω / Cable detached / Poor clamp contact: Red light flashes + buzzer alarm, interlock cuts off the unloading system.
