Modern PLCs originated in the 1960s,and in the decades that followed,common functions and signal paths changed slightly.However,the process control of the 21st century has put forward more difficult new requirements for PLC:higher performance,smaller size and greater functional flexibility.Protection must be built in against potentially damaging Electrostatic Discharge(ESD),Electromagnetic Interference and Radio Frequency Interference(RFI/EMI),as well as high-amplitude transient pulses commonly found in harsh industrial environments.
现代PLC起源于上世纪60年代,在随后的几十年中,通用功能和信号通道发生了少许变化。然而,21世纪的过程控制为PLC提出了更加艰巨的新要求:更高性能、更小体积和更大的功能灵活性。必须内置保护功能,防止潜在的破坏性静电放电(ESD)、电磁干扰和射频干扰(RFI/EMI),以及恶劣的工业环境中常见的大幅值瞬态脉冲。
GP Sorensen-Fuel Pressure Regulator – 800-175
GP Sorensen-Carburetor Repair Kit – #96-419 –
1935 Press Photo Mrs Charles Sorensen Pet Boston Bull
1984 Press Photo Barry Morrell Marilyn Lyric Opera harv
Ford Road 75TH Anniversary 1903 1978 – Lorin Sorensen
The Yellow Star By Deedy, Carmen Agra/ Sorensen, Henri