Electrical Installation for Cranes and Lifting Equipment
1. Scope
This instruction addresses the particular requirements of electrical installation systems for cranes, lifting equipment, transport, and other similar equipment such as escalators, conveyors, bridge trailers, winches, scaffolds, etc.
2. General Requirements
The entire electrical installation can be deactivated by a manually controlled general pole switch located on the main circuit. This switch must be readily accessible from the ground, located in the same room or enclosure as the electrical equipment, and clearly identifiable with an indelible label.
Pipelines from the general protection device to the electric lift or drive must be designed to prevent engine starting from causing a voltage drop exceeding 5%.
Only in the case of machinery intended for carrying goods without transport cages are switches allowed to be installed suspended from the tip of the mobile pipe conduits. Mobile command and signaling lines may be placed under the same protective envelope as other mobile lines, even if they belong to different circuits, provided they meet the conditions established in Instruction ITC-BT-20.
In outdoor installations for mobile services using flexible cords coated with polychloroprene or similar, as per UNE 21.150 or UNE 21.027, the structures of all motors, lifting equipment, combiners, and metal roofs of all electrical devices inside or on the boxes, as well as in the hole, must be connected to a grounded point considered as earth.
Equipment mounted on metal structure elements of the building is considered grounded if the structure has been previously connected to the ground and satisfies the following requirements:
- Electrical continuity is ensured, either by construction or through proper connections, protecting them against mechanical, chemical, or electrochemical damage.
- Its conductivity must be suitable for this use.
- Clearance is only permitted if compensatory measures have been studied and adapted for this use.
The steel structure of the box supported by the lifting cables passing through metal pulleys or drums of the hoisting machine shall be considered grounded to provide a safety condition in the electrical connections between them and earth. If this is not fulfilled, a special driver protection device will be installed.
The runways of all crane workshops will be attached to local protection. The driver’s cabin, pens, etc., where the electric drive equipment is installed, must be accessible only to qualified personnel. When its dimensions allow entry, adequate provisions for electrical service facilities in the affected area must be made as set out in ITC-BT-30. These sites will display a wiring diagram of the installation.
3. Safety
3.1. Protection Against Direct Contact
In the collecting system, slip rings, cables, bus bars, and runway assemblies, access to relevant areas of the facility, such as corridors of the sliding guides or aisles of the porta-crane beam, including access points, must be protected against direct contact with live parts, in accordance with paragraph 2 of ITC-BT-24.
In areas where access is only permitted to specially trained personnel, protection should be provided by placing cables or bus bars out of reach, in accordance with paragraph 2.4 of ITC-BT-24. In this case, the volume limit of accessibility is the surface least susceptible to occupation by people, ending at the surface’s limits.
Protection by placing out of reach is designed only to prevent accidental contact with live parts. Cables and busbars must be arranged or protected so that even with an oscillating load, they cannot come into contact with the hoisting rigging or any control cable, drive chain, or similar elements that are electrical conductors.
3.2. Overcurrent Protection
The electrical equipment will be protected by one or more automatic protection devices that act in case of an overcurrent caused by overload or short circuit. This requirement does not apply to equipment designed to withstand current surges.
The operation of overcurrent protective devices for mechanical brake actuators must produce simultaneous disconnection of the corresponding motion actuators. Protective devices, including temperature-sensitive elements (e.g., temperature-dependent resistors or bimetallic contacts) mounted in or on the motor windings in combination with a contactor, cannot be considered sufficient protection against a short circuit current.
4. Section and Cut
4.1. Cut for Mechanical Maintenance
The cut-off switches must be omnipolar and must have means to prevent any unintended commissioning of the facility. On the supply side of the slip rings or bars, a switch must be installed that allows isolation and disconnection of all line conductors and the neutral conductor of the driver installation wiring.
Cranes, lifting appliances, and transport equipment must be equipped with a cut-off switch that allows the wiring to be disconnected during maintenance and repair. Switchgear assemblies should be able to be disconnected. This disconnect should include power and control circuits.
Load cutting means must be located near the switchgear assembly. Active parts of switchgear assemblies that, for safety or maintenance reasons, must remain in service after opening should be marked with a label indicating that they are energized and should not be touched intentionally.
If circuit disconnect switches pass through the rings or bus bars, they should be protected from direct contact with a degree of protection of at least IP2X. Maintenance disconnect switches can be dispensed with if the switches specified in emergency situations are present.