4Q drives and hydraulic couplers

Comparision about AC 4 quadrant drives and hydraulic couplers application for downhill conveyors.
1. Energy saving
4Q drives boast perfect energy saving goal, can reach high power factor up to1, with energy feedback functions, regeneration energy can be returned to main supply, low heat loss of 1%.
Hydraulic couplers feature low energy saving effect, will waste 75% of energy at low speed.

2. Start performance
4Q drives with low harmonic, no harmonic pollution on main supply, low start current of 50% rated current, full process of start controllable, start point and ramp time settable.
Hydraulic couplers are not able to improve start performance, its start current up to 5~7 times of rated current that cause big shock on main supply and motors

3. Installation
Simple and easy to drives, only connect by cables
Hydraulic couplers are installed between motors and load, motors needed to move, occupy large space

4. Safety
On failure of drive, motor can run in bypass way
On failure of hydraulic couplers, motors will stop for repairing of couplers

5. Running precision
4Q drives can realize accurate adjustment of speed that is subject to output frequency, speed can remain constant when load changes.
Hydraulic couplers with low precision, speed is controlled by oil qty and load. Speed changes with load.

6. Maintaining cost
Low cost for 4Q drives, no need of consumption material
Hydraulic couplers needs regular replacement of oil