Mine Hoist Fully Digital AC Variable-Frequency Speed Control System (High Voltage)

Product Overview

Variable-frequency speed control is an emerging automation technology that has developed in recent years. It achieves stepless speed regulation over a wide range for AC motors by varying the frequency of the controlled object. Our company has applied this technology to mining hoisting equipment.

The fully digital AC variable-frequency speed control system (high voltage) for mine hoists consists of a power supply incoming and outgoing switchgear, a frequency converter cabinet, a switching cabinet, a networked intelligent operator console, a human-machine interface, an encoder, and PLC control.

Product Model Designation Method

Use

The all-digital AC variable-frequency drive system (high voltage) is suitable for motor voltage ratings of 6 kV and 10 kV. It is primarily intended for non-explosion-proof applications, both aboveground and underground. This system is applicable to single-rope winding mine hoists (winches) and multi-rope friction hoists driven by AC variable-frequency motors. It can be used with newly installed hoists (winches) and is also well-suited for retrofitting existing hoist (winch) control systems. Furthermore, this system is applicable to various types of mine hoisting operations, including single-level and multi-level hoisting in main shafts, as well as single-level and multi-level hoisting in auxiliary shafts, and can accommodate both single-layer and double-layer cage systems.

Features

The high-voltage variable-frequency drive system features energy feedback functionality (using AFE control), enabling it to feed electrical energy back into the power grid when the motor is operating in generating mode.

The variable-frequency control system adopts a one-to-one configuration, with one frequency converter driving one motor. The variable-frequency speed-control system is connected to the main power supply system at a voltage level of 6 kV or 10 kV and is used for variable-frequency speed control of the motor. The variable-frequency speed-control system receives control signals from the on-site master control system, driving the hoist motor to operate at variable speeds. In the event of a fault in the high-voltage frequency converter, the system can switch over to operating the motor at industrial frequency.

Main protection functions

(1) Two sets of PLC control systems are employed, with the two sets of communication channels monitoring each other. One set remains in standby mode, truly achieving PLC redundancy. The safety protection circuit adopts a dual-wire system and offers diverse configurations.

(2) It can provide safety protection functions including overtravel protection, slack rope protection, reverse rotation protection, encoder failure protection, speed-limiting protection throughout the entire travel range, depth indicator failure protection, overpressure and undervoltage protection for brake oil and lubrication oil, high-voltage switch tripping protection, main motor overcurrent protection, and direction-memory function for set commands.

(3) Equipped with manual, semi-automatic, fully automatic, maintenance, rope inspection, and emergency start-up functions.

(4) Implement control using software, with the travel-based setpoint and closed-loop velocity control achieved through PID regulation.

(5) Fully digital, with electronic pulse signal input and manual brake control, and featuring a zero-position locking function.

(6) Adopt a modular structure so that, once a circuit malfunctions, it can be quickly modified.

(7) Faults in the safety circuit and key control stages are indicated by 20-segment language alarms.

(8) The control system has been equipped with self-check, alarm, signal memory functions, as well as corresponding graphical and digital displays.

(9) Interlock with the signaling system and the operating system.

(10) Implement the control function for the hoist’s hydraulic braking system, enabling secondary braking (engaging secondary braking during lifting operations, and releasing it after deceleration during lowering operations and when the hoist is in lifting mode). Also implement interlocking with the lubrication station.

(11) It features comprehensive protection functions, including two independent protection systems for safety safeguards such as full-speed overspeed, overspeed in the deceleration zones at both ends of the shaft, and overtravel in either direction. At the same time, it can also perform monitoring and protection functions for fixed-point speed surveillance and brake shoe wear.

(12) Implement continuous speed envelope monitoring and protection, as well as stepwise speed monitoring and protection functions.

(13) Implement the function of digital travel and realize the display of the elevator’s position based on digital travel.

(14) Redundant function with a safety circuit.

(15) Adjustable gate current automatic control.

● The working gate is controlled by PLC software and a safety circuit.

● The brake oil pressure can be adjusted manually.

It is possible to switch between the hydraulic station and the lubrication station in a dual-system configuration.

Technical Parameters