Calculating tool clarifies energy saving potential

Pumps and fans with fixed-control drives are still in widespread use. In this case the constant speed is designed for maximum delivery rate, i.e. maximum volumetric flow. Analyses show that pumps and fans are rarely operated in the full load range. The average flow rate, i.e. volumetric flow, is far below maximum performance. Volumetric flow is usually controlled by conventional mechanical means, such as throttle valves, vane, bypass or on/off controls. In this case the motor operates at maximum speed, regardless of the volumetric flow actually required. Since pumps and fans usually feature long annual operating times, they thus account for a relatively large proportion of energy costs.

Nowadays frequency converters can be used to adjust the delivery rate of flow generating units to actual current requirements. In the case of pumps and fans, for example, this results in energy savings of up to 50%.

The potential savings and the amortization period for the investment in frequency converters can be calculated easily and quickly using SED2 EasySave. The program calculates the energy requirements of the variable-speed drive system on the basis of the system's characteristic data and compares it with the conventional system. The difference is expressed as the energy saving in kWh, which is multiplied by the current energy purchase price. The cost saving is then displayed in the selected currency. Additional savings can be identified in reduced maintenance effort and lower loading on the motors. SED2 EasySave compares total savings with total capital costs (including purchasing, planning, engineering, systems integration, commissioning) and calculates the amortization period required. This often amounts to only a few months. Savings beyond the amortization period can contribute significantly to improved energy efficiency over the entire product life cycle and account for a quantifiable proportion of savings on operating costs.

Power consumption when operating with a frequency converter (red curve) compared with mechanical control of volumetric flow using a throttle valve (blue curve) reveals significant potential for savings. The green area shows the energy savings potential as a function of volumetric flow.

SED2 frequency converters are used for energy-optimized speed control of pumps and ventilating motors. They are equipped with EMC (electromagnetic compatibility) filters as standard features and can therefore be used without any difficulty in the residential, business, commercial and industrial sectors. The low-harmonics technology incorporated as a standard feature also reduces harmonic distortion of mains power supplies to a minimum. This technology is important, since the growing number of electronic devices (computers, fluorescent tubes, etc.) impose a reactive power load on electric power networks and thus cause a significant deterioration in energy supply efficiency.

SED2 frequency converters are equipped with integrated energy consumption meters to enable energy consumption to be monitored directly. They also reduce noise emissions as well as mechanical wear and optimize operating costs in addition to energy consumption.