GE 12HFA51A42H

Description

12HFA51A42H

MUTLI CONTACT AUXILIARY RELAY

HFA TYPE

125 VAC

SELF-RESET

MULTICONTACT AUXILLARY

In 1969, American Digital Equipment Corporation (DEC) developed the first programmable controller, which was used in the production line of General Motors, replacing the relay control system on the production line, and ushered in a new era of industrial control. In 1971, Japan began to produce programmable controllers. Germany, Britain, France and other countries have successively developed and popularized programmable controllers suitable for their own countries. In 1974, China also began to develop and produce programmable controllers. The early programmable controller was designed to replace the relay-contactor control system, used for on-off control, with logic operation, timing, counting and other sequential control functions, so it is called programmable logic controller (PLC).

With the rapid development of microelectronics, computer technology and digital control technology, by the end of 1980s, PLC technology has been very mature, and has expanded from switch logic control to computer digital control (CNC) and other fields. The PLC produced in recent years has made new breakthroughs in processing speed, control function, communication ability and other aspects, and has developed towards the integration of electrical control, instrument control and computer control. The performance and price ratio has been continuously improved, and has become one of the pillars of industrial automation. At this time, the functions of the programmable controller are not limited to logic operations, but have the functions of continuous analog processing, high-speed counting, remote input and output, and network communication. The International Electrotechnical Commission (IEC) renamed the programmable logic controller PC (Programmable Controller). Later, it was found that its abbreviation was the same as that of Personal Computer, so the abbreviation of PLC was used again.

At present, PLC has become the standard equipment for industrial control in the world’s advanced industrial countries, and its application has covered almost all industrial enterprises. PLC technology has become the trend of the world and one of the three pillars of industrial automation (PLC technology, robotics, computer-aided design and manufacturing).