News
News from year: 2019
09/12/19
Danieli Speed Detection System takes a step towards safer crane operation
Innovative system allows complete supervision of hoisting kinematic chain, detecting possible breaks.
Danieli Centro Cranes offers an innovative, new system for safe detection of crane hoist speeds. The target is to improve prompt intervention of safety devices in case of any unforeseen breaks in the hoisting kinematic chain.
The system includes these devices typically installed on modern cranes:
Unlike the classic system design, which detects only a single over-speed threshold at top speed, the solution implemented by Danieli guarantees the following controls:
This system allows complete supervision of the hoisting kinematic chain, detecting potential breaks in it.
The difference between the Classic and Danieli Overspeed intervention is shown below, considering a hot-metal crane lifting at the nominal speed of 10m/min, driven by a motor with nominal speed of 1.500 rpm.
Considering a fault at 600 rpm, the Danieli system intervenes at 10% higher than the reference speed or 660 rpm.
The Classic system intervenes at 10% higher than the nominal speed, or 1.650 rpm.
As shown by diagrams, with the Danieli system braking is anticipated at 600 ms, compared with classic systems, leading to a 43% reduction in braking space.
To achieve these performances, the system continuously compares the actual speeds of drums, the actual speed of motors and the reference speeds and commands coming from the operator.
The installation of absolute safe encoders on the drums brings many other advantages, too:
This obviously leads to a dramatic reduction in the mechanical stress and wear on the emergency brake pads, to an overall improved safe intervention in case of breakage, as well as to improved equipment performance.
The system includes these devices typically installed on modern cranes:
- Safety PLC and related coding;
- Safety absolute encoder installed on drums and
- Incremental encoder installed on motor.
Unlike the classic system design, which detects only a single over-speed threshold at top speed, the solution implemented by Danieli guarantees the following controls:
- Machine standstill control, during which the brake status is evaluated even during standstill conditions;
- Constant control between the real reference speed and the actual hoisting drum speed;
- Constant control between the reference direction and the real direction of the hoist drum;
- Constant control of the speed of the two drums in case of two hoisting drums.
This system allows complete supervision of the hoisting kinematic chain, detecting potential breaks in it.
The difference between the Classic and Danieli Overspeed intervention is shown below, considering a hot-metal crane lifting at the nominal speed of 10m/min, driven by a motor with nominal speed of 1.500 rpm.
Considering a fault at 600 rpm, the Danieli system intervenes at 10% higher than the reference speed or 660 rpm.
The Classic system intervenes at 10% higher than the nominal speed, or 1.650 rpm.
As shown by diagrams, with the Danieli system braking is anticipated at 600 ms, compared with classic systems, leading to a 43% reduction in braking space.
To achieve these performances, the system continuously compares the actual speeds of drums, the actual speed of motors and the reference speeds and commands coming from the operator.
The installation of absolute safe encoders on the drums brings many other advantages, too:
- It integrates the function of rotary limit switches. It is no longer necessary to set them manually: they will be preset and adjusted on the operator panel, with a drastic set-up time reduction.
- It integrates the servo-assisted adjustment of the lifting positioning.
This obviously leads to a dramatic reduction in the mechanical stress and wear on the emergency brake pads, to an overall improved safe intervention in case of breakage, as well as to improved equipment performance.
Autore: JD