TRADITIONAL HYDRAULIC VS SERVO-HYDRAULIC SYSTEM
In the traditional hydraulic system, an Induction motor drives the constant pump at a fixed speed & proportional valves are used for pressure and volume control. As the motor runs at a constant speed and coupled with the constant pump it consumes electrical energy continuously, even during unloading conditions also.
Disadvantages of traditional hydraulic system
- High electrical energy consumption, as motor,, rotates with constant speed.
- Increase in Hyd. Fluid temperature due to constant output of the pump.
- More hydraulic maintenance cost due to increase in fluid temperature Hyd Seals, ‘O” rings life get reduce.
- A bigger heat exchanger requires to maintain hydraulic fluid temperature.
- Operating cost high.
Advantages of traditional hydraulic system
Less initial cost as standard motor & pump used.
In servo hydraulic system, servo motor speed is controlled by servo drive as per the input signal from machine controller for flow & Pressure. In unloading condition or pressure hold condition motor speed will be almost zero. As per flow & pressure requirement motor speed will varies.
Advantages of servo hydraulic system
- Electrical energy saving 60-70 % in GDC and LPDC and 25-50 % in HPDC machines.
- Reduces Hydraulic fluid temperature, as no flow during unloading or no operation conditions.
- Longer hydraulic components life due to less heating.
- Smooth and flexible change-over between pressure-and volume control
- Pressure control in 125μs-loop
- Very low pulsation of pressure and flow rate, So Excellent control behaviour and improved process quality.
- Flow & Pressure control proportional valves not require, as it is control from servo system.
- Operating cost low.
Disadvantages Servo hydraulic system
Higher initial costs