2004-05-18 - - AF1650 is the most compact 3-pole 1650A block contactor in the world
- Electronically controlled operating coil handles large voltage drops
The new AF1350 and AF1650 contactors from ABB have been developed to meet the growing need for high capacity compact 3-pole block contactors. They are designed for use as main or isolation contactors (AC-1) but can also be used in inductive circuits as bypass contactors. A high level of reliability is provided by the electronically controlled coil, which is capable of handling large voltage drops (up to 55 percent), and typical applications for the AF1350/1650 contactors will be generator sets, wind power installations, soft starters and drives.
The AF1350 and AF1650 contactors are the latest addition to ABB’s well established A/AF range and further extends its coverage from 1000A to 1650A. In AC-1 applications they are rated 1350A and 1650A respectively at 1000V and 40° C ambient temperature. They can also be utilized in AC-3 applications between 220V to 440V, where the AF1350 is rated at 860A and the AF1650 at 1050A. The two new contactors share common external dimensions and ABB believes that the AF1650 is the most compact 1650A block contactor in the world.
The new contactors are fitted with three fully rated main poles and two normally open and two normally closed auxiliary contacts, while up to four additional auxiliary contact blocks may also be fitted. The coil covers a wide voltage range from 100 to 250V AC and DC and separate low voltage inputs for PLC control are provided as standard.
Electronic coil interface
In common with all ABB AF contactors, the AF1350/1650 contactors benefit from the AF electronic coil interface. This supplies just the current needed to close the contacts, and then reduces the current to keep them closed, even if the control circuit voltage or power supply quality vary. The elimination of contact bounce or chattering increases reliability and service life, reduces RF interference, cuts power consumption by around 50 percent, and results in less noise when compared with conventional AC contactors.
AF contactors are particularly useful in installations where the power network can experience momentary interruption or variation in voltage. This would cause a conventional contactor to break and immediately make again when the voltage stabilises. The break causes an electric arc, and if the contacts make again before the arc has gone out they can become welded together. This unpredictable behaviour is both hazardous and damaging to the equipment. Previously such installations have had to use expensive rectifiers or DC contactors to prevent this problem.
Unlike conventional contactors which can normally only operate between 85 percent and 110 percent of the lower limit of the coil voltage, the AF coil reduces the drop-out voltage to 55 percent. So in the case of the AF1350 and AF1650, which have a coil rated between 100V to 250V, the contactor coil will hold in until the voltage drops as low as 55V.
The AF design also has a particular advantage for large contactors, such as the AF1350/1650, which consume very high current as the contact system closes. With a conventional contactor set-up, this current can be high enough to require an additional smaller contactor to act as an interface with the control system. However, the AF electronic coil system incorporates inputs for controlling the contactor with low voltage signals, such as from a PLC. This effective separation of the supply voltage from the operating voltage eliminates the need for the additional contactor.