Hertz Kompressoren UK’s Frecon Series VSD compressors for efficiency and long life (April 2012)
Hertz Kompressoren UK has introduced its HSC Frecon Series 18-275 variable-speed rotary screw compressors. With the support of a frequency inverter, these compressors – available as belt-driven or direct-drive VSD models – accurately adjust the motor speed in accordance with the air demand of the factory. Energy consumption keeps decreasing almost linearly in proportion with the capacity, reducing energy consumption by as much as 35 per cent. Also, the wide capacity ranges allow the Frecon Series compressors to supply the required amount of pressure continuously and at a constant level. With these benefits, not only are additional energy savings made possible, but the potential for unfavourable pressure change effects on some critical equipment are also prevented.
Soft Start system
The Frecon series includes further high-end technology features in the form of the Soft Starters, rather than the more traditional star delta starting method. The use of the Soft Start system – available for all power ranges within the Frecon series – extends the motor’s service life and avoids the negative effects of the high start current on the energy system. In addition, the Soft Start system allows the motor to start as many times as is required, while the short idle time periods can result in additional energy savings.
There are a number of other advantages offered by a Soft Start system. From an electrical standpoint, these include: benefits for the electrical network; minimised starting currents; the elimination of current spikes; a reduction in voltage drops on the network; optimised cabling; and minimised inrush current with no transition spikes. In term of mechanical benefits afforded by the Soft Start system, these include: minimised stress on transmissions such as gearboxes, belts and bearings; substantially reduced maintenance costs; and reduced downtime. These advantages can result in up to 35 per cent of a Frecon Series compressor's total cost being saved after a five-year application period.
The Frecon series compressors are fitted with electric motors that meet IE2 efficiency class (motors that meet IE3 effiency class are optional). The motor safety factor has been increased to 1,2 – 1,4 with larger motors. They also offer increased radial force resistance due to a special bearing, shaft and lubrication design and come with full after-sales support.
The Frecon Series’ electric motors offer high efficiency even at low speeds due to the inclusion of high-efficiency Variable Speed Drives (VSDs). Analogue outputs are included for a secondary VSD drive for fans. Additionally, the Frecon series includes new master/slave functions and a new mod-bus protocol for VSD Communication. Frequency controllers of these VSD compressors are high-qualitydrives featuring one brand and one Model VLT for the whole compressor series. They are very user-friendly with an easy-to-follow menu structure, and the controllers are also easy to install, with no need for any setup on the VSD drive. An additional benefit is that of the strong worldwide after-sales service.
With the VSD for the fan, a constant temperature is achievable, potentially resulting in major energy savings. The heat regime is fixed by controlling the fan revolution speed according to the airend temperature with a secondary drive. Constantly running at the airend’s most efficient temperature is achieved, resulting in energy savings on the main motor. This also results in little or no temperature fluctuations, which extends the life of all components within the Frecon compressor.
The compressors are also fitted with controllers for improved functionality, reliability and a number of new functions; these include the ability to record used total energy levels. Additionally, Frecon models also feature aPID activation timer to prevent the airend from speed up without sufficient lubrication, and a PID activation temperature parameter to prevent the airend from cold speed-up.
The high-efficiency airends used on the Frecon series are supplied by the world’s leading airend manufacturers. They are designed based on a new rotor profile and lobe combination, which is the result of long experience of screw compressor performance, new CAD methods and utilisition of modern production technology.
Cold start option
In Winter time and in cold environments compressor oil has a higher viscosity and therefore cannot produce adequate levels of lubrication during start up. Because of this, screws can wear and fail easily. To overcome this situation the HSC Frecon Series air compressors include heating cartridges assembled in a separator tank to warm up the oil. This keeps the oil at a temparature that makes start ups during cold periods effective, without any failure or risk of damage to the screws.
The HSC Frecon Series includes an efficient cooling system to ensure the compressors run at a continuous optimum temperature. A ‘Plate/Bar’-type aluminium oil/air combi-cooler is fitted as standard to all models within the series, and promotes extended compressor life.
Photo caption: HSC Frecon 90.
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