Power connection

A safe and adequately sized power connection is the basis for the reliable use of electrohydraulic technology on the construction site and in existing buildings. Especially in applications such as concrete demolition, strip-out, or rock processing, the continuous power output of hydraulic power packs and the connected tools such as concrete demolition shears or rock and concrete splitters depends directly on the quality of the power connection. The following article classifies the term from a technical perspective, shows requirements and typical practical solutions, and relates them to the products and application areas of Darda GmbH-objective, standards-aware, and practice-oriented. In addition to dimensioning and protection, power quality, voltage stability, and low impedance of the feed are decisive for maintaining hydraulic pressure and predictable cycle times.

Definition: What is meant by a power connection?

A power connection is understood to be the electrical connection of devices or systems to a suitable energy source. This includes providing the correct supply type (e.g., single-phase 230 V or three-phase 400 V), the appropriate plug-and-socket device, correct protective devices, and compliance with safety measures. When operating hydraulic power packs that drive tools such as concrete demolition shears, Multi Cutters, or rock splitters, the power connection determines whether power, torque, and hydraulic pressure can be delivered stably.

Technically, a professional power connection considers at least the following aspects for dependable operation of Hydraulic Power Units and connected tools:

• Electrical parameters: Correct voltage and frequency, adequate short-circuit current available at the point of connection, and acceptable voltage drop under load.
• Interface and compatibility: Coordinated plug-and-socket devices, verified phase sequence, and clear labeling of circuits.
• Protection and monitoring: Suitable overcurrent and residual current protection, and provisions against undervoltage and unintentional restart.

Requirements on the construction site: Power planning for demolition and deconstruction

For work in concrete demolition and special deconstruction, strip-out and cutting, or rock excavation and tunnel construction, the power supply must be planned early. In addition to the available connection voltage, peak loads, cable lengths, protective devices, and environmental influences must be taken into account. Practical planning also evaluates simultaneity factors, expected duty cycles, ambient temperatures, and the quality of temporary distributions.

Supply types and plug systems

• Single-phase 230 V AC: For smaller consumers and auxiliary equipment. Long extensions can lead to voltage drop and loss of performance.
• Three-phase 400 V: Common for high-performance hydraulic power packs. In practice, standardized CEE plug-and-socket devices with coordinated protection are used. Phase sequence and direction of rotation must be checked.

Where construction power is provided via temporary distribution, clearly assigned outlets, mechanical interlocks, and phase rotation monitoring help avoid misconnections and protect equipment.

Load profiles, inrush currents, and protection

Electric motors of hydraulic power packs often draw an increased inrush current at start-up. The sizing of cables and protective devices must take these short-term peaks into account. Soft starters or variable-frequency drives can reduce peak loads but do not replace careful dimensioning in accordance with the manufacturer’s specifications and applicable standards. Time-delayed or sequenced starts for multiple units limit overlap of inrush currents and reduce nuisance tripping.

Cable lengths, cross-sections, and voltage drop

The longer the supply lead, the greater the voltage drop-with noticeable effects on pump speed, hydraulic pressure, and thus on the working performance of concrete demolition shears and rock and concrete splitters. Remedies include sufficiently large conductor cross-sections, high-quality cable reels (fully unwound), and short distances between distributor and power pack.

• Target values: Plan for low voltage drop (typically ≤ 3 to 5% under load), verify loop impedance, and document measured values during commissioning.
• Routing: Avoid tight bends, heat sources, and parallel runs with high-interference cables to reduce thermal stress and electromagnetic influence.

Power connection for hydraulic power packs in conjunction with tools

Darda GmbH relies on electrically driven Hydraulic Power Units for numerous applications. Their stable operation is a prerequisite for reliable force transmission to tools such as concrete demolition shears, Multi Cutters, combination shears, or rock splitting cylinders. Selecting the right supply voltage, the appropriate plug-and-socket device, and correct protection are central building blocks of deployment planning.

Key selection criteria for the power connection include continuous output capability, tolerance to short load peaks, power factor, and the expected duty cycle of the tool. Balanced three-phase loading and appropriate hose and cable management sustain constant hydraulic pressure and reduce thermal stress on equipment.

Use with concrete demolition shears indoors

During strip-out and cutting in buildings, electrohydraulic methods are often used to avoid emissions and reduce noise exposure. A cleanly planned three-phase power connection with sufficient cable reserves ensures that the concrete demolition shear achieves constant cutting and crushing forces-even on thick components or heavily reinforced concrete. Coordinated distribution with residual current protection, documented phase rotation, and reserved circuits for peak consumers increases availability.

Rock and concrete splitters on large construction sites

In rock demolition and tunnel construction, or natural stone extraction, splitting cylinders are powered by hydraulic power packs. Especially in tunnels with long cable runs, minimizing voltage drop is crucial so that splitting pressure and cycle times remain stable. In remote areas, a generator can replace the grid supply if it is sized appropriately for continuous output, inrush current, and power factor.

For generator operation, voltage regulation with low total harmonic distortion and adequate short-term overload capacity helps avoid nuisance tripping and performance losses of the hydraulic power pack.

Protection and safety at the power connection

Work on electrical circuits requires specialist expertise. Safety notes are generally of a general nature and do not replace case-by-case assessment by competent persons. During operation, the applicable electrical safety rules and the procedures specified by the operator apply.

• Residual current protection: Use suitable RCD protective devices in accordance with requirements.
• Cable protection: Appropriate overcurrent protection and mechanical protection against crushing, abrasion, and moisture.
• IP protection rating: Select equipment and distributors according to environmental conditions (dust, splashing water).
• Cable management: Fully unroll cable reels, avoid trip hazards, secure transitions.
• Emergency stop and undervoltage: Observe devices for safe shutdown and to prevent unintentional restart.
• Operational control: Establish switching and locking procedures, ensure clear responsibilities, and maintain access control to distribution boards.

Normative basis and inspections

Construction site distribution boards, extension cords, and connected equipment must be inspected at defined intervals. The applicable standards and accepted engineering practice are authoritative. Test reports document proper condition and provide legal certainty within the scope of operator responsibility.

Scope of inspection typically includes visual checks, functional testing of protective devices, measurement of protective conductor resistance and loop impedance, and verification of RCD trip times. Inspection intervals, documentation, and labeling must be consistent and traceable.

Construction power supply, grid, or generator: choosing the right source

Whether an existing grid connection, temporary construction power supply, or generator operation-the energy source must suit the load profile and place of use. For hydraulic power packs, continuous output, short-term reserves for inrush currents, frequency stability (50 Hz), and power factor are relevant. Insufficient reserves lead to voltage dips, increased heating, and performance losses at concrete demolition shears or splitters.

Power quality and low-interruption operation

Fluctuating voltage or phase asymmetries directly affect pump performance and hydraulic pressure. Suitable distributors, adequate cross-sections, and short runs improve power quality. Undervoltage release devices increase safety when restarting after outages.

• Phase balance: Keep three-phase loads balanced to limit neutral currents and heating.
• Continuity: Where feasible, implement time-delayed restarts and selective protection to limit system-wide outages.
• Compatibility: Consider the interaction with other major consumers on the same feeder to avoid cumulative voltage drop and nuisance trips.

Special application areas: tunnels, existing structures, special missions

Depending on the area of application, the requirements placed on the power connection change. In enclosed spaces and tunnels, zero emissions, ventilation, and fire protection take priority; outdoors, moisture, temperature fluctuations, and mechanical loads predominate.

Rock excavation and tunnel construction

Long cable runs and harsh environments require robust CEE connections, impact-resistant distributors, and higher IP protection ratings. For rock splitting cylinders and hydraulic power packs, precise planning of cable routes is crucial to keep voltage drop low.

• Environmental protection: Use strain relief, cable bridges, and protective covers in traffic areas and wet zones.
• Serviceability: Provide intermediate test points and clear identification to speed fault localization.

Strip-out and cutting in existing buildings

When working in existing buildings, existing house connections are often limited. Distributing loads across separate circuits, coordinated operating times for concrete demolition shears and other consumers, as well as documentation of protective devices help avoid unplanned shutdowns.

In sensitive areas, plan for noise and vibration windows, ensure sufficient reserves on selected circuits, and document the configuration so that repeat setups remain consistent and compliant.

Planning, calculation, and documentation

A structured approach ensures availability and reduces downtime. The focus is on load list, protection, cable routing, and test status.

1. Record consumers (rated power, inrush current, duty cycle, power factor).
2. Define the supply source (grid, construction power supply, generator) and plan reserves.
3. Create a distributor and cable concept (cross-sections, lengths, plug systems, protective devices).
4. Calculate voltage drop and dimension cables accordingly.
5. Before commissioning, perform and document visual, functional, and protective-measure checks.

As a rule of thumb, verify that the total voltage drop from source to power pack remains within defined limits under maximum expected load, and record measured values during commissioning alongside settings for protective devices.

Typical mistakes and how to avoid them

• Incompatible plug systems or phase reversal on three-phase circuits.
• Overloaded multi-socket strips instead of suitable construction site distribution boards.
• Cable reels not fully unwound, causing increased heating and voltage drop.
• Undersized conductor cross-section on long supply leads.
• Generators without sufficient reserve for inrush currents.
• Missing or inadequate residual current protection.
• Uninspected cables and distributors without current test markings.
• Insufficient phase balance leading to overheating and tripping.
• Unprotected cable routes across driveways or sharp edges resulting in mechanical damage.

Practical examples: power connection implemented correctly

Interior demolition with a concrete demolition shear: A three-phase-supplied hydraulic power pack is operated via a tested construction site distribution board with a short, adequately sized supply lead. Peak loads are covered by protection reserves; the concrete demolition shear operates with constant hydraulic pressure.

Rock and concrete splitters in the quarry: The generator is sized for continuous output and inrush current. Cable runs are kept short, cables are protected against damage, voltage drop remains low-splitting operations run quickly and repeatably.

Tunnel construction: High protection ratings for distributors, regular inspections, and clear cable routing ensure the supply over long distances. The hydraulic power packs deliver stable performance to splitting cylinders and shears even under harsh conditions.

Existing buildings with limited connections: Loads are distributed across available circuits, start-up sequences are staggered, and power quality is monitored at the distributor. The result is uninterrupted work with reproducible tool performance.

Environmental and emission aspects of the power connection

Electrically driven hydraulic power packs enable low-emission work in many situations. This reduces exposure to exhaust gases and noise, which is particularly advantageous indoors, in tunnels, and in sensitive areas. The prerequisite is a suitable power connection that reliably provides the required power and thus supports efficient work cycles with concrete demolition shears and rock and concrete splitters.

Well-dimensioned power connections also contribute to energy efficiency: stable voltage and correct phase balance reduce current draw for the same hydraulic output, limit waste heat, and extend equipment service life. Documented planning and measurement support consistent performance over the entire project duration.