Braking resistors are used in many industrial sectors. In particular, these resistors are used in devices to control electrical motors (inverter) and are particularly suitable for working cycles with long or frequent braking.
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The technology of the drives mainly concerns motors and frequency converters, for elevators, conveyors, cranes or robotic technologies. The key aspect is the pilot motor control in the industrial sector. The resistors of RESSE provide the necessary dynamic movement, both as braking resistors in combination with a frequency converter, and as series resistors in combination with continuous electric motor. The high performance resistors RESS are able to reliably control such dynamics.
In normal operating conditions in which the motor acts as a generator, the created energy must be discharged through a resistor chopper or a braking resistor. RESS provides several technical solutions for spaces and mechanical requirements.
Soft starting of motors with ring rotor
For ring engines, often used for high power, the starting current must be controlled in order to ensure a “soft start”. Here, starting and adjusting resistors are used, which are shorted when the engine speed increases. For this application fixed resistors with a steel grid are used; multiple sections of resistance are included in a single assembly. RESS can provide the optimal configuration of the starting resistance.
Emergency power supply via battery-powered DC motors
In applications in which a permanent power supply must be guaranteed, often DC motors with battery power are used. Start-up resistors are used for their startup, sized as needed. When, for security reasons, the normal contactor is not used to short circuit the resistor – this resistor can be configured to be able to operate permanently joined to the engine.
Peak input current limitation
When directly inserting three-phase squirrel-cage synchronous motors, large amounts of inrush currents flow, which can cause the nominal current to multiply. Using resistors in series with three-phase stator windings, this peak input current can be limited. With a single-phase stator series resistor or a “soft” starting motor of the squirrel cage motor, the starting torque may in turn be reduced.
Tests of controls with real loads
In the development of the control electronics, the different uses and load cases of the device are controlled with the help of real resistive loads; this often happens simultaneously, on different test benches.
Handling and robotics
Requests for work process improvement and productivity are continuous. For this reason, optimization is necessary also for the management of devices and robots, which help reduce the cycle times thanks to faster movements. RESS offers a wide range of resistors for this scope. In particular the product group with compact, flat resistances provides ideal solutions for installation in small spaces inside the robots.
Permanent startup permanent slowdown indicate higher stress levels for motion systems. If the control is run by servo controller or frequency converters, braking resistors RESS are suitable to carry out this task. Thanks to the different sizes of the profile, the flat resistors are perfectly suited to the available installation space. Using an optional temperature switch, the field of resistor limit can be used optimally; if you recorded a surface temperature to the limit, the controller can process information and adjust the motion profile.
Highest quality standards, limited installation space and particularly low values for electromagnetic compatibility (EMC). These are the main factors that the partners in the medical technology industry require today.
Speed and efficiency are important goals even in the medical industry. For example in the development of magnetic resonance imaging (MRI) scanner, devices must operate with high rotational energy. The braking resistors facilitate this dynamic, reducing the time of medical treatment, thus improving the quality of care for the patient.
The range of uses of the production machine is virtually unlimited. In order to maintain high quality standards and the highest level of productivity, it is necessary to install highly effective drives and to have a continuous monitoring of the process. RESS resistors offer various possibilities for monitoring. It is possible to get an excellent availability on applications used for a longer period of time, close to the upper limit. In normal operating conditions in which the motor acts as a generator, the created energy must be discharged through a resistor chopper or a braking resistor.
The perfect combination between the power source, the technology of welding and, if applicable, robot technology, is a decisive factor for the quality of the welding product. RESS resistors are used in several places in welding devices, whether portable or robot welders.
Few sectors cover, by type of material, shapes and technologies, a spectrum of application as wide as the construction of mechanical tools. Almost all applications are distinguished by their absolute accuracy and the speed of production. RESS resistors are then used as braking resistors in combination with the frequency converter and in the supply of the machines. In order to implement the emergency stop function of a machine, often three-phase resistors are used; these heaters work in direct conjunction with the motor connected to a contactor in the three-phase circuit. The motor windings are therefore shorted in a controlled manner using resistors. The aim is to ensure a braking action which is independent from the chopper unit of the intermediate circuit.
Testing and laboratory technology
Laboratory and testing technology allows you to carry out tests with a very broad power spectrum, which can range from a few watts to several hundred kilowatts.
With a diverse product range of load and lab resistance, RESS offers ideal solutions for many applications.
Elevators and escalators
The trend towards housing developed in height is growing; it is for this reason that the need for lifts and escalators is increasing.
Safety and reliability are therefore a primary objective; RESS supports manufacturers of elevators providing reliable resistors, whether it’s about drives or power supplies.
Mining and oil industry
Mining and oil production machinery are exposed to high levels of mechanical stress. Ever more, increasingly extreme demands emerge related to the presence of high pressure, strong vibration and high pollution; RESS power resistors are designed to meet this challenge also in the open sea.
When you drill deeper, one of the main problems is the rotary movement united with that of lifting and lowering a drill pipe. To control the lowering phase of the device, often RESS steel grid resistors are used, as single phase brake resistors for frequency converters or as three-phase load resistors to support the diesel generator during braking.
Power plant technology
Energy requirements increase continually and conventional power stations and renewable energy forms take on a role of increasing importance. In this way, the issues of safety, environmental compatibility and efficiency are the main priorities for energy suppliers.
The magnetic field of a pulse rotor of a large synchronous generator is typically powered by direct current. In the case of transport, during which the generator is switched off, the magnetic field of the pulse rotor is silenced. Discharge resistors (with a low resistance and high absorbency capacity) play this function reliably.
Solar energy is becoming increasingly important in the global energy landscape, and in our daily lives; small installations on roofs are increasing, as well as large-scale plants.
Plant operators are faced with huge demands from network operators to ensure excellent quality standards of the network. Also the use of resistors contributes to important qualitative improvements.
A key point of the use of wind energy is to reduce the cost of energy. Therefore, RESS supports its clients by providing appropriate and convenient resistors that meet individual needs. Thanks to a modular design, it is able to meet customers’ needs in terms of protection class, dimensioning and mounting type.
When you disable the magnetic field in the generator, very brief peak loads appear that can damage the electronic power components; also high mechanical deceleration may occur that reduce the service life of the mechanical components. “Crowbar” resistors minimize peak loads effectively, thus protecting the plant.
Power electronics in railway engineering is an interesting area, characterized by large amounts of energy combined with great mobile masses.
The pneumatic system in the railway vehicle provides compressed air for the functioning of the various systems, from the brakes to the doors. These key functions have to be available even in the event of a power failure; the system is also designed for operation with batteries. Starting and adjusting resistors of RESS shall ensure that the DC motor of the pneumatic compressor does not absorb too much electric current during starting.
Cranes and heavy duty technology
Accuracy, speed and excellent availability are fundamental qualitative characteristics in the lifting sector (both for light and heavy loads).
RESS offers solutions to meet individual needs, with products for indoor, outdoor and offshore usage.
Maritime and port technology
Both in coast environments with harsh climate, and on the high seas, the salt in the air and water represents a tough challenge for all materials.
The power resistors RESS, designed with steel grid, may face this challenge and can be used on ships, in ports and in other maritime contexts.