Lifting door carts corrective Encoder Selection Considerations！

Lifting door carts corrective Encoder Selection Considerations
    

one. Gantry crane lifting equipment carts particularity:

Safety requirements for lifting equipment door more and more prominent, the concept of safety first and more important in the control, in accordance with the provisions of 40 meters above the large span gantry crane track synchronous rectification control must be installed to prevent the left and right track the door Unbalanced wheel and rail bite, even derailment accident, due to safety requirements, door left and right wheels need to track multiple simultaneous control, speed, location, etc. reliable feedback information directly related to the safe and reliable control, and gantry crane lifting equipment environment particularity, in turn determines the specificity of these sensors and signal transmission choices:

1. Site complex work environment, the inverter, motor and large high and low voltage power supply system, signal cables and power lines are often ranked together cloth, live electrical disturbances more serious.

2. Equipment mobility, more difficult to move long distances to ground.

3. Signal transmission distance requirements far, safety and reliability requirements of high signal data.

4. Synchronization control signal needs to pass real-time high, and reliable.

5. Many outdoor use, protection class, temperature class requirements, site workers and low level of training, the use of the product requires high tolerance.

6. Cost, if poor options, on-site commissioning time, cost several times the cost of the service may be even higher than the encoder.

two. Absolute multi-turn encoders sense carts correction applied:

In the position sensors door lifting equipment, there are potential, proximity switches, incremental encoder, single-turn absolute encoder, multi-turn absolute encoder, etc., comparatively speaking, low reliability potentiometer poor accuracy, using the angle with dead; proximity switches, ultrasonic switches are just a single point position signal without continuous, now most of the selected rotary encoder, then choose exactly what kind of encoder it?

Incremental encoder, the encoder provides accumulated pulse signal, the relative position of the follow-up device to obtain the amount of change by doing the addition, after a power outage the encoder output signal is no longer relying on the subsequent reception device memory save location. In addition, if there is interference field (large motors, frequency), signal interference is poor, there will be error count, leakage meter pulses caused by the accumulated error, and can not reach the two encoder synchronization. Common incremental signals can not be remote, after a power outage carts can not have any slippage, or loss of position. In all these ways, incremental encoder is obviously not suitable for use in the correction of the carts.

Incremental encoder code plate Illustration:


Single-turn absolute encoder, refer to the absolute value of the signal only lap, in this circle, each position by the multi-channel encoded code signal composed of unique code used in lap, power outages and interference is not affected, the only location . But this single-turn absolute encoder can only work within 360 degrees, if the angle measured by the expansion of transmission gears, precision on the poor, the synchronization accuracy can not be guaranteed; and if the direct use of the lap, through follow-up memory device receiving multi loop control (on a multi-turn measurement methods, in fact, and incremental encoders are the same), after a power outage, since the carts by the wind, falling or human movement, the encoder more than half a turn, it may exceed the count punctuate, and lose position; or interfere in the count and the count circle ring just wrong, wrong will be around! Synchronize their carts on both sides are still unable to achieve absolute position. Although the probability of this happening is not, in debugging hard to find, but it is indeed a security risk, the risk in the event of an accident is possible!

Single-turn absolute encoder Illustration:


Absolute multi-turn encoder means 360 after the encoder absolute value measured by the continuing internal ring gear meter encoder, generally up to 4096 revolutions measurement range, the encoder can be really big door lifting machine the safe use of equipment, which is not subject to the impact of power outages jitter can be long-distance, multi-turn several operating characteristics, internal all-digital, interference, can achieve long-distance signal transmission security. So, from the big door machine lifting equipment safety point of view, absolute multi-turn encoder is an inevitable choice.

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