Addition of VFD for Water Pump Systems with Constant Speed up to 75 kW
Pumps
Measure Goal
The goal is to estimate the electricity savings triggered by adding a frequency converter (VFD) for water pump systems with constant speed up to 75 kW with demand analysis. This measure is relevant when analyses have confirmed that the required flow rate is constant, but the current value is too high. The desired flow rate is achieved with reduced pressure. The savings are related to the reduction in flow rate and pressure.
Requirements
Only measures that meet the requirements of the Energy Ordinance (SR 730.01; EnV) can be credited. The additional requirements for the technical characteristics and for the implementation of the measure are set out in Table 1.
| Technology | This measure applies to water pumps including motors with a rated power Pnom (at the shaft) of up to 75 kW that fall within the scope of Annexes 2.9 and 2.7 EnEV. Adding a frequency converter is only permitted if the pump and the motor are newer than: Pnom ≤ 5.5 kW 8 years 5.5 < Pnom ≤ 20 kW 10 years Pnom > 20 kW 14 years |
|---|---|
| Energy efficiency | The new components of the drive system must meet at least the following limit values according to EnEV: Frequency converter Class IE2 |
| The efficiency of the pump before and after installing the frequency converter must be within a range of ± 5% of the pump's optimal efficiency. | |
| Energy analysis / needs analysis | An energy analysis must be carried out to review the needs and sizing of the pump system. This analysis must show the electricity consumption and the efficiency of the system before and after implementation and be carried out by a person qualified according to ISO 14414. |
| Sizing | The total installed rated power of the new system must be less than or equal to the total installed rated power of the old system |
| Implementation | The replacement and commissioning of the new system must be carried out by a qualified specialist or company. |
Proof of compliance
Compliance with the requirements must be demonstrated by the following documents. The documents listed in Table 2 are an integral part of the proof of measure implementation.
- 1.The needs analysis (PDF format) carried out when resizing the new installation
- 2.Invoice documents (PDF, PNG or JPEG format)
- 3.Photos (PDF, JPEG or PNG format) of the old and the new installation, including the rating plates of the devices (pumps and motors)
Would you like to submit your project or need help?
ContactSymbols, Terms and Units
| Symbol | Description | Unit |
|---|---|---|
E | annual electricity consumption | kWh/a |
ΔEeco | cumulative electricity savings | kWh |
f | Factor | — |
Ns | Standard effective duration | a |
Δp | Differential pressure at pump connections | kPa |
Q | Flow rate | m³/h |
t | annual operating hours | h/a |
η_CF | Efficiency of frequency converter | — |
η_P | Pump efficiency | — |
η_M | Motor efficiency | — |
Calculation Formulas
Stromverbrauch der aktuellen Pumpe
The electricity consumption of the current pump is calculated based on the measurement of the electrical power consumption by the system.
Stromverbrauch nach der Sanierung
The electricity consumption after renovation is calculated based on the actually required flow rate and the additional losses due to the frequency converter.
Wirkungsgrad des Frequenzumrichters
The additional losses caused by a frequency converter can be expressed depending on the rated power of the motor.