Drives FAQ's

Answer:
ABB's ultra low harmonic drive solution uses advanced harmonics mitigation
technology that does not require external filters or multi-pulse transformer. These
drives utilize an active front-end rectifier with a LCL (inductor - capacitor - inductor)
filter. The low line harmonic content of the ACS800-U31 and -37 AC drives fulfil the
strictest harmonic requirements including IEEE519-1992 at the drive's input
terminals. This makes ABB's ultra low harmonic drive a simple and compact solution
for low harmonic AC drive.
Answer:
Ultra Low Harmonic is a marketing name applied to the ACS800-U31 and -37
products for indication that these products offer a new alternative to the conventional
low harmonic drive products and the ACS800-U31 and -37 have lower harmonic
distortion levels than an equivalent power 18-pulse solution.
Answer:

For applications requiring braking even when there is incoming supply line loss, the braking chopper will provide braking down to approximately 10% motor base speed. Therefore, in applications where it is critical the load is stopped quickly even if there is power loss, a brake chopper is a good solution.

Answer:

Yes. The ACS800-U31 includes DC Bus Connection Terminals and an external braking chopper (NBRA type) may be applied. For ACS800-37, cabinet built choppers and resistors are available and may be ordered with a plus code.

Answer:

The absolute value of the current harmonics generated by the drive is independent of the load current, meaning that the absolute value of the harmonics is nearly the same at no load as at nominal load. That is why the current waveform looks distorted even when the load current is very low. This is not an issue as the harmful effects of harmonics depend on the absolute harmonic content based on nominal load. For example, the standards like IEEE519-1992 refer to harmonic content as a percentage of the total load current.

Answer:

In principle, one can consider the current distortion generated by an AC drive as fixed, i.e. it does not depend on the character of the network. The voltage distortion depends on the quality of the network. The higher the impedance of the network (weaker the network), the higher voltage distortion is caused by a given current distortion. That is why harmonic requirements are typically given as current distortion. For example, IEEE519-1992 gives maximum allowed current distortion values based on a network's short-circuit ratio.

Answer:

No, AC line harmonics are caused by many electrical devices and are an overall system issue, not just associated with AC drives. The goal of low harmonic AC drives is to contribute less harmonic distortion to the overall system.

Answer:

As usage of electronic and electrical equipment increases, users and utilities are becoming more concerned about the harmful effects of harmonics. This is leading to more stringent power quality requirements