The example presented here is a fixed field (see drawing in point 4), which excludes the presence of slip rings in its mechanical aspect.
The machine's structure has been designed in order to obtain very high thermal conductance. This ensures very contained standard temperatures and ample possibilities of temporary overload. The considerable increase in thermal conductivity was obtained by means of a fan (2) fixed to the induced constant speed of the asynchronous engine, generating forced air circulation.
This solution is particular thanks to the presence of a hollow shaft coupling (1) with which, with immediate simplicity, the UNEL IEC-B5 engine can be connected.
The not inconsiderable advantage that results is the ability to connect and disconnect the engine at any time and with maximum rapidity.
The need to wrap materials originating from rolling machines, drawing machines, cables, pipes, plastic film fabrics, paper, aluminium, etc. at speeds with constant tension, makes GMC the absolutely most suitable solution for its characteristic curves of the induced current coupling, which follow the ideal winding curve within a certain field.
The material's tension is obtained by varying the GMC supply voltage through a simple apparatus (ALC). Once the excitation voltage is set, the torque automatically adapts to vary the diameter of the coil without requiring any external intervention. This avoids the use of diameter sensors, encoders for speed measurement, load cells for tension measurement and dancer rollers for tension control.
In this way, the coupling's natural torque adjustment sees to, in a completely automatic way, a function which must otherwise be programmed with the use of sophisticated and expensive controls.
The core group is made up of an Asynchronous, B5 form three-phase or single-phase UNEL-MEC-IEC engine powered directly by the network.
This excludes, unlike with classic continuous currents, the presence of expensive and bulky intermediate power equipment.
The variable speed engine has got a tachometer generator (6) mounted within it that provides a voltage proportional to the output shaft speed; comparing this voltage with the reference one, corresponding to a predetermined speed, an adjustment is obtained with accuracy up to 0.2% with constant loads and 1% with variable loads with 20% of the maximum torque. With a 4-pole engine, the speed is adjusted from 0 to 1300 revolutions/1' and with a 2-pole engine, from 0 to 2700 revolutions/1' with controlled acceleration.
Thanks to the low power level required, it is possible to employ highly reliable circuits.
We design and build all the necessary electronic equipment, whose operating safety is guaranteed and confirmed by years of continuous service and is verified through minimal maintenance requirements.
GMV (*) induced current coupling for speed control.
GMV (*) induced current coupling for torque control.
GMVF (*) induced current coupling for speed control.
GMCF series (*) induced current coupling for torque control.
Induced current coupling with input shaft. These groups with an input shaft are used when the rotation is taken directly from the machine and not from the engine.
Coupling controlled in speed and torque, with triggering current "E" brake. This is applied in machines where a triggering current brake may be necessary in addition to speed control. Applications: machines that need instant triggering current braking.