Square D had a group that wanted to develop PLC compatible power monitoring. They worked out of the Cedar Rapids circuit breaker plant - before the group moved to Tenessee.
The pilot installation was at an automotive - I think it was a Ford plant. The dedicated circuit monitor was not available yet. The big secret that marketing did not want to get out was that there was the new Symax model 400 in the bottom of the cabinet. It had analog inputs for CTs and PTs. It did calculations for things like totalizations. The 400 had floating-point math capability that was pretty good for the time and the analog I/O was adequate. 'Matrix' and 'Array' instructions could be used to separate the data by times. It had a usable time of day clock. The 400 was a Motorola 68??? based processor with much more power than the earlier Model 300. I think it had a Z80 8-bit cpu so a 300 could not have handled this project.
The more complex things like individual phase data, THD, and so on were not possible with that hardware. The idea for it was to show that power monitoring within a facility with PLC compatible communications was desirable and possible.
I worked as a contactor on the initial prototype C language interface program and the PLC code. The PC used their SyLink board to get on SyNet. I remember agonizing over how to best represent power factor in integer registers. Decisions about cascaded integers were another factor. I look back now with hindsight and realize how I could have done a better job with long-term accuracy on the integrations and so on.
As my involvement in the project wound down the work shifted to full-time Square D guys and construction of the dedicated circuit monitor. I remember meeting a college professor type who was working out the math for the more complex calculations.
Communications on the unit started as Symax only. I think they soon had some sort of multidrop variation of their hardware to keep costs down for larger installations. In the initial engineering there wasn't much thought given as to how to play well with other protocols. Over time Modbus and other things entered in. Modern power meters talk a variety of ways.
The Square D folks had the vision and time and budget and management support to develop a product that changed industry even though the need for it may have not been clear to most people at that time. It and products like it are more important than ever now with the emphasis on energy.
I would hope that companies today would allow engineers with that sort of vision to move ahead with what they see. And to have the long-term sense to do it themselves without sending the work somewhere else. It's exciting to be a contributing part of a creative team. I hope others get the opportunity.
The pilot installation was at an automotive - I think it was a Ford plant. The dedicated circuit monitor was not available yet. The big secret that marketing did not want to get out was that there was the new Symax model 400 in the bottom of the cabinet. It had analog inputs for CTs and PTs. It did calculations for things like totalizations. The 400 had floating-point math capability that was pretty good for the time and the analog I/O was adequate. 'Matrix' and 'Array' instructions could be used to separate the data by times. It had a usable time of day clock. The 400 was a Motorola 68??? based processor with much more power than the earlier Model 300. I think it had a Z80 8-bit cpu so a 300 could not have handled this project.
The more complex things like individual phase data, THD, and so on were not possible with that hardware. The idea for it was to show that power monitoring within a facility with PLC compatible communications was desirable and possible.
I worked as a contactor on the initial prototype C language interface program and the PLC code. The PC used their SyLink board to get on SyNet. I remember agonizing over how to best represent power factor in integer registers. Decisions about cascaded integers were another factor. I look back now with hindsight and realize how I could have done a better job with long-term accuracy on the integrations and so on.
As my involvement in the project wound down the work shifted to full-time Square D guys and construction of the dedicated circuit monitor. I remember meeting a college professor type who was working out the math for the more complex calculations.
Communications on the unit started as Symax only. I think they soon had some sort of multidrop variation of their hardware to keep costs down for larger installations. In the initial engineering there wasn't much thought given as to how to play well with other protocols. Over time Modbus and other things entered in. Modern power meters talk a variety of ways.
The Square D folks had the vision and time and budget and management support to develop a product that changed industry even though the need for it may have not been clear to most people at that time. It and products like it are more important than ever now with the emphasis on energy.
I would hope that companies today would allow engineers with that sort of vision to move ahead with what they see. And to have the long-term sense to do it themselves without sending the work somewhere else. It's exciting to be a contributing part of a creative team. I hope others get the opportunity.