Since the grid suffers great impacts by currents upon starting of fans and pumps and thus becomes unstable; and fans and pumps produce great noise during operation, which affects site personnel adversely, a certain margin (factor of safety or FoS) is reserved to ensure production reliability when designing the power drives of production machinery. In the event that a motor can’t operate under full load, the excessive torque, save that fulfilling the requirement of power drives, adds unnecessary power consumption, which in turn becomes a waste of electricity. The traditional method of speed (flow rate) regulation for fans and pumps is to adjust the openness of inlet or outlet valves (butterfly valves or ball valves). It requires great input, and consumes most of the energy on flow interception of valve system. With variable-frequency function incorporated, the requirement can be fulfilled by simply reducing the revs of pumps/fans when a greater flow rate is no longer needed.

The variable-frequency control cabinet for fans and pumps is an energy conserving cabinet specially designed for fluid conveyance of fans and pumps based on the respect of operation characteristics. It is embedded with technologies of intelligent control, flux and speed estimation and variable-frequency speed regulation. This can essentially eliminate the power waste phenomenon, also known as the “Big horse dragging tiny cart”, which is quite common among fans and pumps as a result of model selection or load variation, so that the equipment may maintain the optimum working order, thus saving power to a significant extent.

Advantages of variable-frequency control cabinet for fans and pumps:

The variable-frequency control cabinet for fans and pumps is a comprehensive energy conserving product that involves a function combination of soft starting + speed regulation + energy conservation module + power factor increase + VAR compensation + harmonic suppression to ensure maximum of energy-saving efficiency.

1. Variable-frequency energy conservation

In can be know from hydrodynamics that P (power) = Q (quantity of flow) × H (pressure), and Q is in direct proportion to revs N raised to the first power, H to N raised to the second power, and P to N raised to the third power. In case that the efficiency of a water pump is certain, the revs N will decrease in proportion with the quantity of flow, and so will the axial output P, but in the proportion of the third power, i.e. the power consumption has an approximate cubic relationship with the revs for motors of fans and pumps. For example: For a 55 kW motor of a water pump, when its revs decrease to 4/5 of the original, the power consumption will be 28.16 kW, saving 48.8% power, and when the revs decreases to 1/2, the power consumption will be 6.875 kW, saving 87.5% power.

With the VFDs for technical equipment from CEAYEA Electrical &Technology (Shanghai) Co., Ltd. installed, the motor will be regulated and maintained at the optimum revs, which will in turn affect the power of the motor, keeping both the motor and the equipment on the best economic equivalent, thus saving the power of the motor.

2. Power-factor-compensated energy conservation

Reactive power increases both line loss and equipment heating. And what really matters is that the decrease in power factor gives rise to a decline in active power, causing considerable reactive power consumed in the lines and thus low utilization rate of equipment and severe waste. It can be learnt from the formulas P = S × COS Ф and Q = S × sin Ф (where S - apparent power, P - active power, Q - reactive power, and COS Ф - power factor) that the active power P increased with COS Ф. The power factors of regular fan and pump motors fall between 0.6 - 0.7. With the variable-frequency speed regulator, the integrated filter capacitor of the VFD will lead to COS Φ ≈ 1, reducing reactive power loss and increasing the power factor, and thus improving the active power of the grid.

3. Soft-starting energy conservation

Since motors are fitted with a DOL or star-delta starter, the starting current is equal to (4-7) times of the rated value, which will impose significant impact upon M&E equipment and the power supply grid and excessive requirement on grid capacity. The great current and vibration occurring during starting will severely damage baffles and valves and affect aversively the service lives of equipment and pipelines. With our variable-frequency control cabinet for fans and pumps, the soft starting function of the VFD will initialize the starting current to zero and limit the maximal to the rated value, so as to mitigate the impact to the grid and the requirement on capacitors, prolong the service lives of the equipment and valves, and reduce the cost of equipment maintenance, while providing convenience and safety for operation.

4. Energy conservation with light load and reduced voltage

The variable-frequency control cabinet for fans and pumps conserves energy by reducing both the load and voltage via the VFD. For the load of driving torque, since little variation has occurred to the revs, a decrease in voltage will not contribute much to energy conservation. However, this is especially different for fans. When less air quantity is required, the motor will decelerate. As we know, the power consumption of a fan is in proportion to the revs raised to 1.7th power, hence the torque of the motor will suffer a great reduction, presenting a considerable energy conservation result.

Note:

1. The cabinets below 18.5 kW are wall-mounted, while the those above 18.5 kW are upright;

2. Please call us first should you have any special requirement;

3. The product may be customized as required;

4. The customer is responsible for the supply of the pressure transmitter. Please indicate in case that our supply is required.