GB/T 12602-2020Safety devices against over1oading for lifting appliances (English PDF)

4.2 Basic requirements

4.2.1 Component identification The exposed operable elements (switches, knobs, etc.) of the device shall have clear and permanent external markings. The identification shall be clear. The text identification shall have at least simplified Chinese.

4.2.2 Material and structure

4.3.2.3 If the power supply is interrupted, the limiter shall retain its settings.

4.3.2.4 The limiter shall have the function of recording dangerous conditions such as working hours, working cycles and overloading actions of the lifting appliances.

4.3.2.5 The limiter with recording function shall have a communication output interface. When a digital communication interface is used, the communication protocol shall conform to the open protocol stipulated by the current national standards, to facilitate users to obtain basic data such as weight/torque.

4.4.1 Rated lifting capacity indicator

4.4.1.1 The rated lifting weight indicator shall have the following functions:

a) When the load reaches 90% ~ 95% of the rated lifting weight, a visual and/or audible warning signal shall be issued;

b) When the load reaches the alarm action value, a visual and/or audible alarm signal shall be issued.

4.4.1.2 The visual and/or audible signals shall be clear and continuous. Once the signal is triggered, it shall be maintained continuously during a working cycle of the lifting appliances, until the overload is removed. Audio warning and alarm signals shall be different, meanwhile there is a clear difference from the environmental noise of lifting appliances. It shall be not less than 75 dB(A) at a position 1 m from the sound-issuing part as well as the position of the operator. The light early-warning signal shall be yellow; the light warning signal shall be red, which shall be clearly visible in the driver's field of vision.

4.4.1.3 The crane operator shall not be able to cancel the warning from the control station, unless the audible and visual warnings are used at the same time under the same condition, in which case the audible warning can be cancelled by operating the manual cancellation device 5 s after its action. If this kind of cancellation device is used, it shall act automatically when the lifting appliances needs to resume the audible warning. The audible warning can be cancelled during the calibration and test of the lifting appliance.

4.4.2 Numerical information indicator

4.4.2.1 Indicators that provide numerical information shall meet the following basic requirements:

5.1.1 Visually inspect the device samples:

a) The structure is firm; whether the assembly parts are loose;

b) Whether the shell has cracks, blisters, scratches and other defects;

c) Whether the assembly positions of sensors, connectors and other components conform to the instruction manual;

d) Whether there are waterproof measures for each connection part and cable hole;

e) Check the quality certificates of the materials used in the main components and check whether they meet the requirements of the design calculations;

f) Whether the exposed operable elements are marked;

g) Whether to install a power supply switch;

h) If the function release switch and audio signal cancellation device are set, check whether they meet the requirements.

5.1.2 Check whether the device samples meet the following requirements:

a) For the parts of the device installed in the lifting appliance's load-bearing system, check the corresponding material quality certificates, design drawings and design calculations, to confirm that their strength shall not be less than the strength of the load-bearing parts in the system.

b) Have the analysis, calculation and processing functions of the dynamic load status of the equipped crane. When necessary, use a signal generator to simulate the dynamic load state, to input the dynamic load signal to the limiter sample.

5.1.3 For the limiter with a force sensor as a force measuring element, connect the sample parts according to the wiring diagram, to form a complete system; check whether it has a self-check function when starting up.

5.2.6 Voltage fluctuation test When supplied by AC power, apply

0.9 times ~

1.1 times the rated voltage for 10 min and 60 min. When supplied by DC power, apply

0.85 times ~

1.35 times the rated voltage for 10 min and 60 min. In the process of step-down and step- up, respectively, check whether the action error meets the requirements according to 5.2.1.

5.2.7 Insulation resistance test Between the power inlet end of the device and the metal part of the shell, it shall use an insulation measuring instrument of the corresponding insulation voltage level (at least 500 V) for insulation resistance measurement.

5.2.8 Power frequency withstanding voltage test The power frequency withstanding voltage test shall be carried out according to the method specified in

8.3.3.4 of GB/T 14048.1-2012.

5.2.9 Cyclic damp heat test

5.3.1.1 After the limiter that uses the force sensor as the load measuring element of the lifting appliance is tested in the laboratory, the limiter is installed on the lifting appliance according to the actual configuration for installation test.

5.3.1.2 When the limiter for measuring the load of the lifting appliances in other special ways cannot be tested in the laboratory, the limiter is installed on the lifting appliance according to the actual configuration for installation test.

5.3.2 Test conditions The lifting appliance used for the test shall be adjusted, inspected and test-run according to requirements. The test site and environmental conditions shall comply with relevant requirements. The accuracy of the test weight shall not be less than 1% and shall meet the requirements of the test range. The device shall be calibrated in advance.

5.3.3 Rated lifting capacity test According to the rated load test methods and procedures in the relevant standards of equipped lifting appliances, lift the corresponding rated load for the test; the lifting appliance shall be able to work normally. For the lifting mechanism with multi-speed transmission performance, each gear shall be tested separately.

5.3.4 Test of combined error and action function and indicator function

5.3.4.1 The test requirements are as follows:

a) For lifting appliances with constant rated lifting capacity: the lifting object shall be braked and stopped at 100 mm ~ 200 mm from the ground, then the device will be activated by gradual loading. The limiter's action function shall meet the requirements of 4.3.1.2; measure the actual lifting capacity. Lower the heavy object to the ground; the control system returns to normal. Use the lifting operation method (including inching) of the lifting appliances to slowly lift the heavy weight again. Check whether the limiter operates reliably.

b) For lifting appliances whose rated lifting capacity changes with the working range and the allowable load-changing amplitude: Prepare a test weight for each test point; lift it with a working range smaller than the test point; gradually increase the working range to make the device move; the limiter's action function meets the requirements of 4.3.1.2. After the actual working range is measured, the corresponding rated lifting weight can be found on the rated lifting capacity chart. If for the actual measured working range, it cannot directly find the corresponding rated lifting capacity from the rated lifting capacity chart, it shall use the calculation method as provided by the manufacturer of the lifting appliance or the other methods

b) After formal production, if there are major changes in product structure, materials, processes, functions, etc., which may affect product performance;

c) There is a big difference between the exit-factory inspection results and the last type inspection;

d) When the product resumes production after stopping production for 1 year;

e) When the national quality supervision agency puts forward a requirement for type inspection.

6.3.2 Type inspection items are as shown in Table 7.

7.3 Transportation and storage

7.3.1 During transportation, it shall avoid direct rain and snow and strong vibration and shock.