L46A1 Mast Section What are the electrical protection measures for tower crane
The electrical control system of tower crane shall be equipped with necessary electrical protection measures to protect the safety of electrical equipment and personnel. The electrical protection measures of tower crane mainly include: Main isolating switch, short circuit protection and voltage loss protection of main power supply, zero position protection, motor overload protection, magnetic loss protection and overspeed protection, emergency power-off switch, limit protection and travel protection, channel port interlock protection and grounding protection.
L46A1 Mast Section：
http://www.towercranesupply.com/product/l46a1-mast-section-for-tower-crane-masts
1 Main disconnector
Generally, the maintenance and inspection of electrical equipment should be carried out under the condition of power failure. Therefore, there should be isolation switch or other isolation measures between electrical equipment and power supply grid. When the disconnector is disconnected, the effective disconnection distance and obvious disconnection point must be maintained, so that the maintenance personnel can visually confirm that the main power circuit is disconnected.
When the air switch and the iron case switch are in the off position, sometimes they are inconsistent with the state, and there is no obvious off point, so they can not be used as the isolation switch. It can only be used as load switch.
2 short circuit protection of main power supply
When the insulation of the electrical equipment on the crane is damaged and the shell or phase to phase short circuit occurs, the short circuit protection device of the main power supply shall act quickly to cut off the fault power supply. The short-circuit protection of the main power supply requires that each phase must be set to ensure that the fuse link of the fuse is blown or the automatic circuit breaker acts in case of short circuit between any two phases or between any one phase and the ground.
When a crane is powered by cable or a group of sliding wires, if the main power switch has been set on the ground and has the short-circuit protection function, the short-circuit protection of the main power supply may not be set on the crane. If multiple cranes share a group of sliding wires and a ground main power switch is set, each crane shall be equipped with a fuse or circuit breaker as the short-circuit protection device of the main power supply.
3. Voltage loss protection of main power supply
L46A1 Mast Section：
http://www.towercranesupply.com/product/l46a1-mast-section-for-tower-crane-masts
The loss of voltage protection of the main power supply refers to the automatic disconnection of the main power circuit after the interruption of the power supply; when the power supply is restored, the main power circuit cannot be connected automatically without manual operation. In general, the button that can be reset automatically is connected to the coil of the main power contactor or the circuit of the voltage loss trip coil of the automatic circuit breaker to realize the voltage loss protection of the main power supply.
If there is no voltage loss protection for the main power supply, and the power supply is restored after the power supply is interrupted, the main power supply can be connected automatically without manual operation. In this regard, sometimes the operator fails to find out that he mistakenly believes that the main power supply is still dead, and if he touches the controller intentionally or unintentionally, it will cause misoperation and accidents.
L46A1 Mast Section：
http://www.towercranesupply.com/product/l46a1-mast-section-for-tower-crane-masts
