3/28/2019

Delta Provides Sustainable Power Regenerative Solution for Crane Applications

The origins of cranes can be traced back to ancient Greece and have historically always found application in construction, cargo operation and many other fields. Although modern cranes still operate under the same principal as their historic versions, there have been massive technological advances to improve the lifting process, including variable-frequency drive systems with motors.

In a variable-frequency drive system with high inertia, such as cranes and elevators, the motor is in a power generating state. Since the rotor is dragged by external forces, the actual motor speed exceeds the inverter-controlled synchronous speed. This quickly feeds energy generated by the motor back to the DC bus, resulting in a rapid rise in the DC bus voltage that can endanger the inverter. This excess energy must be quickly consumed to keep the DC bus voltage within a safe range, otherwise the inverter will either malfunction or enter overvoltage protection mode.

The traditional method is to convert the excess energy into heat by using a brake resistor. This method has the advantages of simpler wiring and lower total cost, but also has the disadvantages of a large brake resistor, a limited braking capability, and inefficient use of energy. The brake resistor also releases the generated energy in the form of heat, requiring additional cooling units for the system not to overheat.

Delta recently provided a customer in the UAE with its Power Regenerative Unit REG2000, to solve these problems within their crane application. The crane system consists of a bridge wheel and a hoist to lift heavy objects and transport them along the bridge to a different location. During operation the bridge wheel travels horizontally, while the hoist runs vertically. Through deceleration and braking, excess energy is created, which the REG2000 can directly convert into electric energy, rerouting it back into the electrical grid. This way the created power won't go to waste and the user can use the newly created electric energy for other applications.



For this application Delta's power regenerative unit provided the following advantages to our customer:

• Compact Design and easy installation: While just as easy to install as a traditional brake resistor with only 6 wiring connections, the REG2000 has a built-in reactor, allowing the customer to save up to 50% of space due to its compact design.

• Improved energy savings: As a substitute for brake resistors that give off excess energy created by the crane, the REG2000 achieves substantial energy-savings thanks to its power transformative nature. Instead of giving off energy as heat, it transforms potential energy into reusable energy with above 95% efficiency.

• Improved Braking Ability: On top of being more efficient, space-saving and sustainable than traditional systems, the power regeneration unit also features an improved braking ability, with 150% compared to the brake resistors 125%.

Delta's REG2000 Power Regenerative Unit is as simple to install as a brake resistor, while only half the size, and it does not require an additional heat dissipation device. The most outstanding feature is that excess energy is collected and converted into reusable electricity for a more sustainable solution, bringing new, green “Automation for a Changing World.”

News Source:IABG Marcom