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Gozuk developed new drives, special for solar pump system, DC input, AC output, DC/AC switchable.
Capabilities of electrical Variable Speed Drives are more advanced now than they were just a year ago. New concepts - including the increasing prominence of the switched-reluctance drive - combined with variations of more proven designs are expanding your options. All this progress may make last year's guidelines passe.
This first part of the two-part series covers various types of drives and their general capabilities. The second part discusses the most common applications of A-S drives and the drive type best suited for an application. For some, more than one drive type will fill the application requirements. Also, various drive manufacturers offer different capabilities for the same type of A-S drive. http://www.acdrive.in/select-the-best-drives-127113.html
Normally the VFD has three curves: linear, nonlinear and S curve, usually most of them choose the linear curve; nonlinear curve is suitable for variable torque loads, like fans etc; S curve is suitable for constant torque loads, the acceleration and deceleration changes relatively slow.
An AC drive will have losses even at full speed, a soft starter will not and it will cost roughly 20% of the price of a similar AC drive (percentage varies with size).
AC Drive: It is primarily used when motor speed control is needed as well as for limiting the starting current. Like soft starters, it also contains the motor protection (hence separate motor protection relay is not required) and start/stop control capability. It is also used for both LV and MV voltage motors.
Motor Protection Relay: It is used for... the protection of medium voltage motors and used to trip the MV motor starter when the fault condition occurs. Motor protection relays have various modules such as overcurrent, short circuit, unbalance, ground fault, number of start/hour, thermal unit etc. Common motor protection relays are Multilin 469 (GE), SEL749 (SEL), IMM 7990 (CEE).
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Based on the features specified for each (AC drive and soft starter) in the weg calatog, the one thing that stands out is the speed control. AC drives have a more accurate speed control, whereas soft starter do not function necesarily to control the speed of motors.
It should be noted that most AC drives and some high-end soft starters will provide most if not more protection features found in many Motor Protection Relays. In the case of AC drives, most inexpensive MPRs are incapable of accurately protecting the motors because they cannot correctly interpret the output current waveform coming from a AC drive, so the AC drive will actually do a better job or providing protection. There are exceptions to this rule as you go to higher priced MPRs and lower priced AC drives of course.
A soft starter cannot change the speed, so if you need to, it will not work. You cannot really compare them in that realm.
AC drives are 5-10 times more expensive than soft starters once you get above about 25A, so you really cannot justify using a AC drive in place of a soft starter unless you have some very specific issues:
An AC drive can allow starting of an AC motor at 100% FLC or less, a soft starter cannot. So if you have a severely limited power source, sometimes an AC drive is your only choice. A soft starter cannot start a loaded motor with less than 200% current, usually 300-450% depending on the type of load.
An AC drive can allow a 3 phase motor to be run from a 1 phase source (with proper selection), a soft starter cannot.
The AC drive should be of equal size to the electric motor or bigger. In some applications requiring high starting torque due to the load characteristics, the AC drives may need to be oversized to suit.
whatever AC drive you pick should be from a supplier who is as LOCAL as possible and can support you when things are not going as planned. Most use the same or similar technology (otherwise they would not survive in the market) and every drive works great when you commission them, until it doesn't.
Two sets 660MW generators in North-China. The condensing pump reconstruction with AC drive in the plant is the first application of 660MW generator in China. It provides experience for 600MW upward generator reconstruction in future.
AC drive in vector control mode has several tuning parameters to increase or decrease motor performance. With factory default parameters a AC drive in vector mode will have higher performance than a drive in V/F mode.
This vector tension control AC drive adopts international current most advanced open tension control technology under fully synchronized torque mode. It not only integrated global super control technologies, but also combines with Chinese tension control application's characteristics to further strengthen the AC drives reliability, stability and simple debugging, which can better meet the requirements of the tension control applications.Tension Control AC drive
This vector control AC drive (also called VFD) is our new generation products include a wide range VFD drives in low voltage for single phase (1.5kW, 2.2kW for 220VAC to 240VAC) and three phase (0.75kW to 630kW for 380VAC to 460VAC), with ingenious appearance & design as well as excellent performance, powerful & stability functions, suitable for a wide range of applications.
Base on working principle, it can be divided into V/F control VFD, slip frequency control and vector control VFD, etc.; Base on usage, it can be divided into general-purpose VFD, high-performance dedicated VFD, High-frequency VFD, single phase VFD and three-phase variable frequency drive.
• Special magnetic flux vector control frequency inverter
• Input voltage: single phage 220V to 240V, three phase 380V to 440V fluctuate range ±15%
• Power range: 1 Phase 0.4kW to 2.2kW, 3 Phase 0.75kW to 500kW
• Close loop control with built-in PID feed...
• Integrated RS485, Modbus-RTU communication protocol
• Built-in braking unit in the frequency inverter with 15kW power or lower
• LCD, LED keyboard for option
• Multi-step PLC control function
• 32 bit high speed CPU special for ac motor control
• Programmable terminals for convenient control
• Check and adjust parameters online