A control cabinet is the functional hub for power distribution, control, monitoring, and safety of machines and tools on the construction site and in deconstruction. In applications with hydraulic tools from Darda GmbH—such as concrete demolition shears, rock and concrete splitters, combination shears, multi cutters, steel shears, or tank cutters—the control cabinet coordinates the interaction of the hydraulic power unit, valve technology, sensors, and operation. It ensures that commands like Start, Open/Close, Split, or Relieve Pressure are executed reliably, reproducibly, and safely—even under demanding conditions in concrete demolition, strip-out, rock excavation, tunnel construction, natural stone extraction, or special operations.
Definition: What is meant by control cabinet
A control cabinet is an enclosure that brings together electrical and electronic components for controlling and safeguarding technical processes. It houses switching devices (e.g., contactors, relays), protective and monitoring equipment (circuit protection, motor protection, residual-current protection), controllers (e.g., PLC), indication and operating elements (pushbuttons, indicator lights, emergency stop), as well as interfaces (connectors, terminals, radio and cable interfaces). In contrast to a large-format switchgear cabinet, the control cabinet is often more compact, mobile, or mounted close to the machine and tailored to a specific function—such as the safe operation of a concrete demolition shear or a rock and concrete splitter. The goal is the safe, standards-compliant and robust implementation of switching and control tasks in harsh environments.
Design and components of a control cabinet
The design is determined by the task (power distribution, control, safety) and the operating environment. In applications with hydraulic power packs and hydraulic tools from Darda GmbH, typical functional groups are combined to control and safeguard movements (open/close, forward/back), forces, and pressures in a targeted way.
Enclosure and degrees of protection
The enclosure protects the internals against dust, moisture, impacts, and vibration. Common IP degrees of protection (e.g., IP65/IP66) ensure operation with splashing water, drilling slurry, and dust. Mechanical impact resistance (e.g., IK ratings) and corrosion-resistant materials are important on construction sites and in tunnel construction. A well-sealed cover, cable glands, and proper drainage help prevent condensation.
Power distribution and protection
Within the control cabinet, supplies are distributed, feeders are protected, and drives are safeguarded. Typical components include:
- Main switch and interlocks
- Circuit breakers, motor protection switches, thermal and electronic overload relays
- Residual-current protection (depending on use), surge protection, line filtering (EMC)
- Power supplies (e.g., 24 V DC for sensors/control)
Control technology
Depending on complexity, relay logic or PLC-based controls are used. Solenoid valves on the hydraulic power pack are actuated; pressure sensors and limit switches provide status feedback. In applications with concrete demolition shears, interlocks are common to prevent inadmissible motion sequences, while with rock and concrete splitters the focus is on a safe pressure build-up and relief sequence.
Operating elements and indication
- Emergency stop as a mushroom pushbutton, wired for functional safety
- Command pushbuttons (Start, Stop, Open/Close, Split, Relieve Pressure)
- Selector switch (operating modes: manual/automatic/service)
- Indicator lights/displays for readiness, fault, pressure reached
Interfaces and communication
Wired hand-held controls, connectors for valve manifolds, potential-free contacts for enables, and optionally radio control with safety-related signal transmission. In larger systems, fieldbuses or serial interfaces are possible—with vibration-resistant connectors and strain reliefs in dust- and shock-exposed environments.
Function in concrete demolition, special deconstruction, and rock excavation
In deconstruction and natural stone extraction, the control cabinet coordinates the interaction of hydraulic power, tool motion, and safety functions. Examples:
- Concrete demolition shears: Control of opening/closing, holding functions, pressure monitoring, interlock to prevent unintentional closing when a guard position is open.
- Rock and concrete splitters: Sequence control for pressure build-up, splitting impulse, and pressure relief; feedback when splitting pressure is reached; monitoring of temperature and duty cycle at the power pack.
- Combination shears, multi cutters, steel shears: Soft start, end-position logic, load monitoring to avoid overload.
- Tank cutters: Special consideration of spark avoidance through appropriate switching device selection and EMC measures; clear separation of control and power circuits.
Actuating hydraulic power packs
Start/Stop of the power pack, pump selection, switching between pressure/flow rate, valve enables, and pressure limiting are logically linked in the control cabinet. This allows movements to be executed in a targeted and reproducible manner.
Pressure and force control
Setpoints and limits are monitored via pressure switches, sensors, or analog signals. This is essential for splitting operations and for cutting with high force.
Interlocks during tool change
The control cabinet can issue enables only after pressure relief and tool acknowledgment. This prevents unintended start-up of hydraulic components.
Selection criteria for control cabinets in harsh environments
Selection depends on location, tool, power demand, and safety requirements:
- Degree of protection and robustness: IP protection, shock and vibration resistance, UV resistance, corrosion protection.
- Temperature range: Starting capability in cold conditions, heat dissipation under continuous load; condensation management.
- EMC and power quality: Mitigation measures with frequency converters, long cables, and generator operation.
- Safety functions: Emergency stop, safe enables, interlocks; design based on risk assessment.
- Service access: Clearly wired terminals, clear labeling, sufficient space reserves.
- Cable management: Strain reliefs, kink-free routing, abrasion-resistant jacket materials.
- Modularity: Expandability for additional sensors or further valve sections.
- Documentation: Circuit diagrams, terminal plans, bills of materials, test records, unambiguous designations.
Installation and commissioning
Proper installation is a prerequisite for safe operation, especially in mobile applications in deconstruction or tunnel construction.
Mounting location and fastening
The control cabinet is mounted for accessibility, protected from splashing water, and with minimal vibration. Heat ingress from sun exposure or the power pack’s exhaust is avoided. For mobile use, shock-absorbing mounts are advisable.
Wiring and labeling
Conductor cross-sections, ferrules, color-compliant core identification, and clear terminal markings simplify maintenance and troubleshooting. For hand-held controls and sensor circuits, tread-resistant connectors are important.
Testing and functional acceptance
Before operation, insulation resistance, protective conductor continuity, phase sequence (for three-phase consumers), emergency stop function, interlocks, and all operating modes are tested. The machine leaves the assembly area only after documented acceptance.
Safety-related functions
Safety functions are defined according to the risk assessment. Typical measures include dual-channel emergency stop circuits, safe enables, monitored valve return, and defined stop categories. In applications with concrete demolition shears and splitters, uncontrolled motions and pressure spikes must be avoided. Performance and safety levels are determined by applicable standards; a project-specific evaluation is essential.
- Emergency stop: Redundant design, force-guided contacts, clear labeling.
- Enable chains: Mode selector switch, door/lid monitoring (if present), pressure relief as a start condition.
- Diagnostics: Fault messages with clear assignment (e.g., Valve A stuck, pressure switch B not reached).
Maintenance, inspection, and troubleshooting
Regular visual and functional checks increase availability and safety. Maintenance intervals depend on usage intensity and environmental conditions.
- Open the enclosure; visual inspection for moisture, dust, loose parts.
- Tighten terminals, check connectors, inspect seals.
- Functional test: emergency stop, operating modes, end positions, pressure switches.
- Thermography or temperature measurement under load during continuous operation.
- Update documentation: changes, spare part replacements, test results.
Typical faults and remedies
- Loose terminal/connector: leads to sporadic failures—tighten terminals, check strain reliefs.
- Condensation/corrosion: dry, replace seals, use dehumidifier if necessary.
- Thermal trip: check load profiles, improve ventilation, correctly size protective devices.
- Defective operating elements: replace pushbuttons/switches with mechanical wear in good time.
Environmental conditions, degrees of protection, and materials
Concrete dust, moisture, salt exposure (e.g., in tunnel construction), temperature fluctuations, and vibration require robust enclosures, high-quality seals, and vibration-proof mounting. Materials such as powder-coated metal or high-grade plastics are selected based on weight targets, corrosion risk, and impact loading.
Documentation, labeling, and retrofits
Complete documentation with circuit and terminal diagrams, cable lists, operating manual, and spare parts list facilitates operation and service. Retrofits—such as additional pressure sensors, further valve sections for combination shears, or extended operating logic for rock and concrete splitters—are cleanly documented, labeled, and tested.
Practical examples from application areas
During strip-out, the control cabinet controls compact hydraulic power packs for concrete demolition shears directly inside the building; a wired hand-held control enables finely metered movements with minimal spark and dust risk. In tunnel construction, particularly high requirements for IP protection, EMC, and vibration resistance must be met. In natural stone extraction, the control cabinet prioritizes a process-secure pressure sequence for splitters to achieve clean fractures. In special operations—such as with limited power supply—a robustly designed power path with monitoring ensures reliable operation.
Future topics: condition monitoring and digital signals
Sensors for temperature, humidity, and switching cycles enable predictive maintenance. Event logs and clearly structured diagnostic signals reduce downtimes. Even in harsh environments, this improves availability and process quality—without compromising simple, robust operability.
Demarcation and classification
The term control cabinet is used in practice for compact, machine-proximate units. Larger, stationary installations with extensive power distribution are often referred to as switchgear cabinets, while portable operator boxes appear as hand-held control units or control panels. For hydraulic applications with tools from Darda GmbH, a clear division of tasks has proven effective: the control cabinet consolidates operation, protection, and control logic; the hydraulic power pack delivers the power; the tool-side mechanics (e.g., concrete demolition shear, rock and concrete splitter) safely convert the commands into force.