Gantry cranes with reliable protections can work more safely and efficiently during material handling operations. No matter what kind of gantry crane you select, you expect it works the way as it is supposed to be. There is some information on electric protections for the gantry cranes in the following:
Electric Protection System for Gantry Crane
Short circuit protection: the main power supply circuit sets automatic air switch as crane’s short circuit protection; control circuit sets small volume automatic air switch as the short circuit protection.
Voltage loss protection: circuit configuration has voltage loss protection; when the crane is powered again after the power cut-off, it is needed to push the start button again to operate the crane, which eliminates the possibility that the crane operates automatically after the power is on.
Emergency power off switch: the crane sets rotary reset type emergency power off switch to cut off the main power supply and control circuit of the crane under emergent circumstances. The switch is installed at the place where people are easy to operate it.
Overload limiter: when the load reaches 90% of the rated lifting capacity, the limiter will send informatory warning signal; when the load reaches 110% of the rated lifting capacity, it will cut off the lifting power supply and send prohibitive alarm signal.
Travel switch: the lifting mechanism sets up and down fire stopper as the limit switch of the lifting range, and it also has protective effect against adhesion of controller. The crane sets operating limit limiter which consists of travel limit switch and safety ruler, the limit switch is installed on the crane, and the safety ruler is installed on the bearing rail beam without affect the crane traveling to make sure the crane travels in the safe range. The crane limiter can be common limit switch or also can be photoelectric switch or laser anti-collision device which is smaller, has higher performance and more accurate limit distance.
Zero position and interlock protection: cabin control crane has the functions of zero position protection and door switch interlock protection. The zero position protection makes sure that the crane will not operate automatically when the power supply is restarted after the power cut-off, avoiding accidents. Door switch interlocking makes sure that the personnel or some items will not fall down from the door because the safety door is open or the crane operates suddenly.
Protection of phase failure, phase dislocation, over voltage and under voltage: the integrated protector of the crane circuit system has the protection function of phase-failure, phase dislocation, over-voltage and under-voltage, when the above four circumstances happen, it will cut off the crane main power supply automatically to avoid personnel injury and equipment damage.
Grounding protection: metal mechanism and all the electric equipment metal enclosure, tube groove and low voltage side of the transformer are equipped with reliable grounding, the total grounding resistance is not greater than 4Ω, and it allows the crane track is used as grounding wire. The crane insulation resistance against ground at ambient temperature is not less than 1MΩ.