Load limiter installation: QCX load limiter

Load limiter is widely used on the hoist and crane to ensuring the operation saftey. How to install the hoist load limiter? The following instruction of QCX Load Limiter is given for your reference. 

1、Sensor installation

First, check whether the product nameplate models and specifications are consistent with the crane capacity, rate, and tighten screws everywhere. Generally, there are two ways to install the Sensor: bearing type and fixed pulley style. (Note: The sensor can be installed at one end of the non-transmission of power) as shown in Figure 1.
Note: If the sensor is installed in outdoor use, you should add rain cover.

Figure 1:1. Wire rope, 2. Hook, 3. Reducer, 4.Rope drum,
5. Sensor, 6.Fixed pulley, 7. Fixed pulley shaft, 8. Senor, 9, Shaft seat

2、Installation and wiring of the electrical control box

• （1）Open the instrument box, with two M6 screws fixing the instrument to the expediently observation position on the driver's cabin. Installation should be strong, if the cabin has too strong vibration, it should take appropriate anti-vibration measures. Electrical control box dimensions are shown in Figure 2.

Figure 2 QCX load limiter

• (2) It shall not be installed in direct rain and strong corrosive media environments.
• (3) Electrical control box the AC power line should connected to end crane power, not controlled by other electrical equipment.
• (4) After the electrical control box installation is completed, line by line standard cable racks suspended from the crane trolley moves together. VA, ⊥, V +, V- connection corresponding to not take the wrong mark. VC is a test point.
• (5) The connection between the sensor and the electrical control box with RVVP 4 × 0.4 mm2 shielded cable, the sensor must be reliable grounding shield. Instrument power cable supply terminal (~ 220V connection 1, 2 terminals; ~ 380V connection terminals 1, 3), the control line connected J1, J2 terminal, so J1, J2 series with the crane hoisting control loop. Selection of soft rubber wire and cable, low voltage control loop, the control line should be as rough, if the control voltage is ~ 36V or less, the control line should bold to 1.5 mm2.
• (6) The housing must be grounded, installation and wiring should comply with GB3811-2008 "crane design" requirements.

3. Load limiter adjustment and installed for testing

After sensors and electrical control box installed and wiring has been completed, according to the following steps to check and adjust the system and installed for testing.

• (1) Check the power supply into the line-to-ground (housing) insulation resistance, available 500V shake table measuring not less than 1 MΩ.
• (2) Turn on the power, the weight of the display should be bright and display numbers.
• (3) Self-test function checks, self-test button is pressed on the instrument box, the number of values displayed in the alarm value or more, you should cut off the lifting control circuit, cranes stop up the job and at the same time sound and light alarm signal that the overload control the system is working properly.
• (4) The adjustment elements are arranged according to the position of Figure 3, as the following steps to adjust:

Figure 3 Load limiter adjustment

A. System Zero alignment: crane hook one meter off the ground, open the electrical box cover, located on the circuit board side to adjust potentiometer RP1, the display number is zero, if the transfer is less than zero, you can 1R5 4.3K resistance appropriate to reduce, or increase the appropriate 1R3 5.1K, to expand the span adjustment range.

B. Showing the value of the full value alignment: lifting rating of 80% to 100% of the standard weight of known weight or object (error is less than ± 1%), adjust the circuit board "benchmark" the display value potentiometer RP2 Consistent with the weight of the object, such as not adjust, you can toggle SW4 secondary magnification change, expand the full value of the adjustment range. If still not adjust the adjustable positive "full value" RP4. Under normal circumstances, SW4 "2" dial to ON, other are allocated to OFF, 1 ~ 4-bit DIP, DIP digital large magnification too large. (If the rating Vc → ⊥ voltage + 2.8V, this time Needless to adjust the alarm point.)

C. Alarm point adjustment: Although the factory before the unit tested adjustment, but in the field there is a need to re-examine, 105% to 110% of rated load lifting weight Standards Act or a known weight of the object, there should be sound and light alarm, delay of 1 to 2 seconds off the lifting loop power. If the alarm high or low, you should align the RP3 potentiometer adjusted until date, if the conditions to deal with immediate alarm test, namely lifting 130% load there should be sound and light alarm, immediately cut off the lifting loop power.

When lifting the rated load capacity of 90% to 105% of the objects, should intermittent audible alarm, but do not cut off the lifting loop power control, suggesting that the operator can’t be increased the weight.

If you want to hoist overload test, control lines can be removed, but the unit can be displayed the weight.

• Description (1) J1, J2 to control the relay normally closed contact, during normal operation the relay does not operate. When overloading, J1, J2 off and cut off the lifting loop power.
• (2) This device is a traffic safety protection equipment, installation and commissioning of the unit should use security technology department attended, adjusted after passing the test can be put into use.