Contactors gain easy fitting connection bar kits

An ABB Automation Tech (LV Products) product story

Edited by the Engineeringtalk editorial team Mar 12, 2003

A new range of fast and easy-to-fit connection bar kits is the latest addition to ABB's large A line series of contactors from 145 to 750A.

A new range of fast and easy-to-fit connection bar kits is the latest addition to ABB's large A line series of contactors from 145 to 750A (75kW to 400kW motor power AC-3 utilisation).

They enable ABB to meet the growing demand for a systems approach to low voltage motor control and protection components by offering pre-assembled connection bar kits for star-delta starters, reversing starters and phase to phase connection as well as connection between a contactor and MCCB/switch fuse.

ABB has designed the contactor connection bars to be much easier to fit than conventional preformed cable connections, saving time and assembly costs with the added advantage that they are flush fitting which also helps to save space in the panel.

All the panel builder has to do is take the appropriate kit from the box, fit it into position and tighten up to create a neat, tidy and aesthetically appealing finished assembly.

All main terminals on the large A contactors are already well protected, however for total protection ABB also offers a wide range of terminal shrouds.

ABB's large A contactors provide complete coverage of virtually any contactor requirement from 145 up to 750A across three ranges: A145 to A300 (145 to 300A), AF400 to 460 (400 to 460A) and AF580 to AF750 (580 to 750A).

One of the their key features is an innovative 'upside down' design which puts the coil at the top and contacts at the bottom.

This enables them to form a single, harmonised system with direct connection between contactors, circuit breakers, switchfuses and overload relays providing safe motor control and protection to meet type 2 co-ordination requirements (IEC947.4.1).

To complement the large A contactors ABB offers a range of accessories including thermal overload relays, auxiliary contact blocks, surge suppressors and mechanical and electrical interlocks together with the new connection bar kits.

Electronic coil control is now available on all the large A contactors and is standard on the AF400 upwards - these AF contactors can be used in a much wider voltage range, from 24 to 500V, and for both direct and alternating current The AF electronic coil interface 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%, and results in less noise when compared with conventional AC contactors.

The 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.

The AF electronic coil interface has a particular advantage for large contactors, 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.

AF electronically controlled coils cover a wider voltage range than conventional contactors, with just three coil options (24-60V DC, 48-130V AC/DC and 100-250V AC/DC) needed to cover a voltage spectrum that previously required a number of different coil variants.

This enables panel builders and distributors to stock fewer coils than with conventional contactors.