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D E S C R I P T I O N:
The P280 is a single phase welding control, manufactured exclusively by H&H Resistance Welders, a
division of ERON Corporation, Afton, Oklahoma. Utilizing the latest in Large Scale Integration (LSI)
digital circuitry, the entire control has been kept under 60 cubic inches in volume which includes solid
state relays and power transformer.
The heart of the P280 is a Motorola Micro Controller, running at an operating speed of four million cycles
per second. Using a sophisticated computer language, the Micro Controller is capable of thousands of
decisions in a fraction of a second, thus, allowing itself to stay well ahead of possible problems.
Some of the special circuitry and software which has been designed into the P280 has to do with power line
monitoring. The software constantly monitors the incoming voltage level to allow itself time to respond to
variations which could cause problems. The P280 will not take away the final control of the welding
sequence, nor does it modify the heat depending on line voltage variations. The P280 does have circuitry
to constantly search phase shift variations for either 50 or 60 cycles/second. An extremely valuable monitor
circuit is the power input fluctuation monitor, which has a convenient indicator located on the Power Supply
Input Output (PSIO) board on the rear of the CPU. At any time, it can be observed for line drops, spikes,
or noise. Although the P280 has extremely good digital noise filters, it gives the customer an additional
analytical tool to prepare for future electrical problems.
The use of LSI hardware has resulted in a very small Central Processor Unit (CPU). The CPU board
measures 4 x 4.25 x 1.5 inches. The inputs and outputs are accomplished through a screw type barrier
terminal on the rear of the PSIO board. 18 gauge wire can be used for all interconnections to the welder.
Fuses are supplied for separate protection of 120 vac and CPU power.
The P280 can be mounted in any position and in any cabinet using the pre-punched chassis or panel. The
standard stand alone cabinet is 8 inches wide, 10 inches high and 6 inches deep. This cabinet houses the
control with PSIO board and required step down transformer and firing board be mounted externally. The
SCR fired system can be housed in one cabinet, which will include the PT500/IF500 firing board, SCR
pack, Step down transformer, and line board. The dimensions of this assembly are 16 inches wide, 14
inches high and 6-3/4 inches deep.