With the continuous development of China's construction industry and the improvement of construction mechanization level, the requirements of construction elevator’s manufacture and technical level of all-in-one machine are getting higher and higher; its operating conditions directly affect the construction progress. The traditional construction elevator generally uses the contactor - relay control, direct start and mechanical brake forced braking, and the large brake impact has greatly affected the service life of mechanical structure.
Elevator adopts variable frequency speed to solve the above problems, which has greatly improved the performance and safety of construction elevator.
2. Structure of elevator
The main components of construction elevator are as follows: rail frame, cage, transmission system, wall-attached frame, chassis fence, electrical systems, safety protection devices, cable power supply devices.
Ordinary construction elevator has a poor comfort due to adopting the direct start and stop of industrial frequency. In order to upgrade the start and stop comfort, some manufacturers install the inverter to the construction ladder, and the system adopts a contactor - relay + inverter control mode, but the frequency drive is basically only used for speed control. And the device can be equipped with PLC control module and floor calling and leveling device. The construction elevator installed with leveling device can be better controlled and more accurately stops in the required floor; the calling device of installing floor is convenient for information circulation and management.
The electrical system introduced in this paper is the frequency conversion and adjusting speed of construction lifting all-in-one machine, The internal integrated signal logic processing of inverter has a rich expansion capability while replacing the PLC, which has tightly combined the variable frequency, speed regulation and contactor control system.
3. Composition of all-in-one machine speed control system
All-in-one machine speed control system integrates signal logic control, inverter control, contactor control, brake unit, overload protection, brake brake circuit together, which can realize the control protection function of elevator control cabinet with smaller volume, lower cost, better performance and stronger power.
4. On-site equipment situation
On-site construction ladder drive mechanism is the 3 motor worm gear drive system.
The specific equipment is as follows:
Motor: 3 sets Jiangsu Sanshang YZZ132M-4 motor, each rated power 11KW, rated current 24A, voltage 380V, rotational speed 1390 r / min.
Reducer: 3 Jiangsu Sanshang, the model LPJ-287, each rated power 11-15KW, reduction ratio of 16: 1, worm type.
Brake brake: 3 Jiangsu Sanshang, model MZZ2-1.5 / 175, rated voltage 195Vdc, current 1.1A, insulation F grade, braking torque 175N.
Configuration all-in-one model: GD300-39-037-4, inverter rated power 37KW, rated output current 75A.
Customer demand: positive and negative direct switching, overload capacity.
Construction ladder all-in-one machine
5. All-in-one system debugging
5.1 Debugging of variable frequency speed control system
After ensuring the main circuit and control circuit IO terminals is correctly wired, the system starts power on commissioning.
First step: Restore the release values, set the parameters of motor ;
Second step: the calibration of weighing function ;
Third step: light load test running;
Fourth step : overload, security and other test.
5.2 On-site debugging results
Load 2T 50 Hz ascending current waveform
Repeatedly test positive and negative rotation and direct switching, good switching comfort, without a sense of falling.
6.Features of all-in-one machine frequency conversion system
(1) Customized protection design
Customized protection design for construction elevator application features, ensuring the reliable running of equipment in high temperature, humidity, dust outdoor space.
(2) Flexible installation
A flat structure design, support wall and embedded installation, the embedded installing does not occupy a cage space with more efficient usage space of the cage;
(3) Convenient maintenance
Adopting the modular design concept, electric and inverter part are layout respectively, optimize the layout of electrical components, simplifying maintenance procedures; Push - pull fan, ensure that the positive maintenance of fan, reduce the product failure rates;
(4) Powerful terminal function
a) all master control signals, limited protection signals are configured with the standalone terminal, and set corresponding signal indicator, which can quickly determine the fault location and reduce the maintenance workload.
b) Input / output terminal adopts redundancy design; the terminal can be directly replaced when it’s damaged, high maintenance efficiency, low maintenance costs.
c) Provide AC220V AC power connector, which can be directly used to cage power electric equipment to meet the cage fan, lighting and other power requirements.
d) Terminals detachable.
e) Hardware emergency stop
Logic control circuit adopts interlocking design of hardware and software, emergencies are directly realized by hardware protection, meeting the relative requirements of GB 26557-2011 “personnel and material construction hoist with a vertical – oriented cage”, reliable and safe shut down.
f) Dual brake interlock system
brake system adopts dual relay + dual contactor interlocking mode with auxiliary contacting points in series, when contactor adhesion occurred, it’s possible to reliably cut off brake power supply and implement downtime.
(5) Low voltage logic control
Adopting the whole DC low voltage logic control scheme can effectively improve the security of operating system, and isolate the strong and weak electricity with better system reliability.
(6) Low voltage response
Low - voltage response scheme is applied in the power grid environment of construction site, ensure the power supply of control system meeting the requirements of contactor action and the safe and stable operation of equipment.
(7) Special phase - lacking protection function
adopting dual phase - lacking protection of hardware and software, meeting the industrial requirements of GB 26557-2011 “personnel and material construction hoist with a vertical – oriented cage”, optimize it according to industry characteristics, effectively avoid the power off of control circuit, reduce emergency stop and ensure safe and comfortable at the same time.
(8) Low load and speed upgrading
Upgrading the running speed in low load, greatly improving the device working efficiency.
Verified by on-site test, the safety protection facilities of the control system is sound and easy to test, without impact and decline when the elevator starts and stops, with steady running. Application of all-in-one inverter system has reduced the shock to reducer, coupling and other mechanical devices and power grid, which is convenient for the system maintenance and has improved the working efficiency, gained the reorganization of customers.