The requirements of the "Safety Regulations for Lifting Machinery" on the electrical equipment of cranes

1 General requirements

The electrical equipment of the crane must ensure that the transmission performance and control performance are accurate and reliable, and can cut off the power supply and stop safely in an emergency. Do not arbitrarily change the circuit during installation, maintenance, adjustment and use to avoid failure of the safety device.

The installation of crane electrical equipment must comply with the relevant provisions of GBJ232-82 "Code for Construction and Acceptance of Electrical Installation Engineering".

2 Power supply and circuit

2.1 Power supply

The crane should be powered by a dedicated feeder. For AC 380V power supply, when a flexible cable is used for power supply, a dedicated core wire should be prepared as a grounding wire; when a sliding wire is used for power supply, a dedicated grounding wire should also be provided for occasions with high safety requirements, that is, four sliding wires. String.

All power supplies with a phase voltage above 500V shall comply with the relevant regulations for high-voltage power supply.

2.2 Dedicated feeder main circuit breaker

A main circuit breaker should be installed at the inlet end of the feeder dedicated to the crane. The outlet end of the main circuit breaker should not be connected to other equipment unrelated to the crane.

2.3 Crane main circuit breaker

A main circuit breaker should be installed on the crane, and it should have the function of breaking the circuit when it is short-circuited. It is not necessary to install the main circuit breaker on the small single-girder crane that is operated on the ground.

2.4 Main line contactor

The crane should be equipped with a bus contactor, which should be able to shunt and break the power circuit or control circuit of all mechanisms. When the air switch of the main mechanism has been installed on the crane, the main line contactor may not be provided.

2.5 Control circuit

The crane control circuit should ensure that the control performance meets the requirements of the mechanical and electrical system, and there should be no error circuits, parasitic circuits and false circuits.

2.6 Remote control circuit and automatic control circuit

Any mechanism controlled by the remote control circuit and the automatic control circuit should automatically stop working once the control fails.

2.7 Lifting electromagnet circuit

On AC cranes, the lifting electromagnet should be equipped with a dedicated DC power supply system, and there should be a backup power supply when necessary.

2.8 Feeding bare wire

• 2.8.1 The safety distance and deviation between the crane feeder bare wire and surrounding equipment should meet the requirements of Table 16. Otherwise, safety protection measures should be taken.
• 2.8.2 The contact surface of the sliding wire should be smooth, free of rust, good electrical conductivity, and properly installed. Compensation devices should be installed when crossing the expansion joints of the building.
• 2.8.3 Safety signs of slip line

The main slide wire of the power supply should be painted with red paint on the non-conductive contact surface, and a safety sign or an indicator light indicating live electricity should be installed at an appropriate position.

2.9 Wires and cables

The crane must use copper core multi-strand wires. Generally, rubber insulated wires and cables are used as wires. When using a multi-strand single core wire, the cross-sectional area shall not be less than 1.5 square millimeters; when using a multi-strand multi-core wire, the cross-sectional area shall not be less than 1.0 square millimeters. There are no regulations on the cross-sectional area of the connecting wires for electronic devices, servo mechanisms, sensor components, etc. that can be confirmed to be safe and reliable.

The wiring inside the electrical room, control room, control panel, protection box, small cross-sectional area wires of the main circuit and the wires of the control circuit can be plastic insulated wires.

Ship cables should be used for cranes working in ports.

2.10 Cable reel and retractable device

Cable-powered cranes should be equipped with cable reels or other retractable devices when the moving distance is more than 10m. The cable retracting speed is synchronized with the crane running speed.

2.11 Electrical wiring

• 2.11.1 For cranes working outdoors, the wires should be laid in metal pipes, and the metal pipes should be treated with anti-corrosion treatment. If it is replaced by metal wire duct or metal hose, it must have good rain and corrosion resistance.
• 2.11.2 For cranes that work indoors, wires should be laid in trunking or metal pipes. The cables can be laid directly. Protective measures should be taken where there is mechanical damage, chemical corrosion or oil erosion.
• 2.11.3 The wires of different institutions, different voltage levels, AC and DC should be separated when passing through the pipe. The lighting line should be laid separately.

3 Safety requirements for main electrical components

3.1 General requirements

The electrical components should be compatible with the mechanical characteristics, working conditions and environmental conditions of the crane. When working under rated conditions, the temperature rise should not exceed the rated allowable value. If the working conditions and environmental conditions of the crane are changed, the electrical components should be changed accordingly.

3.2 Automatic switch

The automatic switch should remove dust at any time to prevent mutual arcing; and should be checked and repaired frequently to ensure that the contacts are in good contact and the terminals are firmly connected.

3.3 Contactor

The contactor should be checked and repaired frequently to ensure flexible and reliable action, clean iron core end face, smooth contact, and close contact to prevent adhesion and jamming. Reversible contactors should be checked regularly to ensure reliable interlocking.

3.4 Overcurrent relay and delay relay

The action value of overcurrent relay and delay relay should be adjusted according to design requirements. Do not short-circuit the contacts arbitrarily.

3.5 Controller

The controller should be flexible in operation, clear in the gear position, clear in the zero position, and reliable in operation. The operator of the controller should strive to reduce, and should not arbitrarily remove the positioning components.

The movement direction of the operating handle or hand wheel should be consistent with the direction of the mechanical movement.

The upright handle should be equipped with a protective device to prevent the circuit from being connected due to accidental collision.

3.6 Brake electromagnet

The armature of the electromagnet should move flexibly and accurately, without blocking, and the contact surface of the iron core should be in close contact with no abnormal sound when it is pulled in. The stroke of the electromagnet should meet the design requirements of the mechanism.

The middle air gap of the electromagnet should meet the original design requirements.

4 Electrical protection device

4.1 Main isolation switch

The main isolation switch should be installed at the crane inlet, or other isolation measures should be taken. Small single-girder cranes that operate on the ground can be omitted.

4.2 Emergency power off switch

The crane must be equipped with an emergency power switch. In an emergency, it should be able to cut off the crane's main control power supply. The emergency power off switch should be located in a place that is convenient for the driver to operate.

4.3 Short circuit protection

• 4.3.1 A main circuit breaker should be installed on the crane to realize short-circuit protection.
• 4.3.2 When the mechanical mechanism of the crane is driven by a cage-type asynchronous motor, a short-circuit protection should be provided separately

4.4 Loss of voltage protection and zero protection

The crane must be equipped with loss-of-pressure protection and zero-position protection.

4.5 Loss of Excitation Protection

DC shunt, double-excited, and separately excited motors should be equipped with loss-of-excitation protection.

The power consumption braking and eddy current brake speed regulation system of DC power supply shall be equipped with loss-of-excitation protection.

4.6 Overcurrent protection

• 4.6.1 Each set of mechanisms must be individually equipped with overcurrent protection. Exceptions are the mechanisms and auxiliary mechanisms driven by cage-type asynchronous motors.
• 4.6.2 Three-phase wound motor can be equipped with overcurrent protection in two phases. For the system protected by a protective box, a total overcurrent relay protection should be installed on the third phase of the motor.
• 4.6.3 The DC motor can be protected by an overcurrent relay.

4.7 Overspeed protection

The main hoisting mechanism of casting and quenching cranes, as well as the hoisting mechanism and luffing mechanism of cranes that use thyristor stator voltage regulation, eddy current brake, energy consumption braking, thyristor power supply, and DC unit power supply speed regulation, should have overspeed protect.

4.8 Grounding

• 4.8.1 Grounding range
  • The metal structure of the crane, the metal casing, pipe grooves of all electrical equipment, the metal sheath of the cable and the low-voltage side of the transformer should be reliably grounded. Maintain good grounding during maintenance.
• 4.8.2 Grounding structure
  • 4.8.2.1 The metal structure of the crane must have reliable electrical connections. Cranes working on rails can generally be grounded through wheels and rails. If necessary, set up a special grounding wire or take other effective measures.
  • 4.8.2.2 The grounding wire should be connected with flat steel with a cross-section of not less than 150 square millimeters or copper wire with 10 square millimeters by welding. The grounding wire connection should be inspected in accordance with the provisions of Part 15 "Grounding Device" of GBJ232-82 "Code for Construction and Acceptance of Electrical Installation Engineering".
  • 4.8.2.3 It is strictly forbidden to use the grounding wire as the current-carrying neutral wire
• 4.8.3 Requirements for grounding of lifting electromagnet
  • For the lifting electromagnet rectified and powered by the AC power grid, there must be a reliable electrical connection between the housing and the crane.
• 4.8.4 Requirements for grounding of the suspension control button station
  • There must be a reliable electrical connection between the metal shell of the suspended control button station and the crane.

4.9 Grounding resistance and insulation resistance

• 4.9.1 Grounding resistance
  • The grounding resistance of the grúa de la pista and the grounding resistance of any point on the crane shall not be greater than 4Ω.
• 4.9.2 Insulation resistance to ground
  • When the power supply voltage of the main circuit and the control circuit is not greater than 500V, the ground insulation resistance of the circuit is generally not less than 0.5MΩ, and in a humid environment not less than 0.25MΩ. Use a 500V megohmmeter to perform the measurement at room temperature.
  • Insulation mats should be laid on the floor of the cab.

5 Lighting, signal

• 5.1 The crane should be equipped with normal lighting and portable lighting.
• 5.2 The lighting should be equipped with a dedicated circuit. The power supply should be tapped from the inlet end of the main circuit breaker of the crane. When the main circuit breaker cuts off the power supply, the lighting should not be cut off. All kinds of lighting should be equipped with short-circuit protection. It is strictly forbidden to use metal structures as loops for lighting circuits. A single battery is used for power supply, except for systems with a voltage not exceeding 24V.
• 5.3 The portable running lights should be powered by a double-loop transformer not greater than 36V, and autotransformers are strictly prohibited. It must also meet the requirements of 2.4.8.2.3.
• 5.4 The illuminance of the crane driver's indoor lighting should not be less than 30lx.
• 5.5 The illumination of the crane's machine room, electrical room and special elevator for machine maintenance shall not be less than 5lx.
• 5.6 Obstacle lights
  • Outdoor cranes with a total height greater than 30m should be equipped with red obstruction lights in one of the following situations.
    • a. When there are no buildings and other facilities higher than the top of the crane nearby;
    • b. When there is a possibility of collision;
    • c. When it may become a dangerous obstacle for the aircraft to take off and fly.
  • The power supply of the obstruction light shall not be cut off due to the influence of the stop of the crane.
• 5.7 The crane should have a signal indicating the opening and closing status of the main power supply, and if necessary, a fault signal or alarm signal should be set.
  • The signal indication should be set in a place where the driver or related personnel can see and hear.
  • The electrical system is an important part of the crane. When in use, the electrical part of the crane must be designed, installed and used in strict accordance with the "Safety Regulations for Lifting Machinery".

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