YS170 Single-loop Programmable Controller (DISCONTINUED)

Most SLPC and YS170 controllers in the field contain a custom program stored on an EPROM in the case of the SLPC and in NVRAM in the case of the YS170. When upgrading from an SLPC or YS170 to a YS1700, it is necessary to either rewrite the program in YS1700 language or convert the program from SLPC or YS170.

Both centrifigal and axial compressors cannot be allowed to operate below the surge limit of the operating conditions. The machinery may be exposed to excessive stress and vibration. If the discharge flow demand is less than the compressor surge limit, some of that flow must be vented or recycled to the inlet to stay above surge.

Both centrifigal and axial compressors cannot be allowed to operate below the surge limit of the operating conditions. The machinery may be exposed to excessive stress and vibration. If the discharge flow demand is less than the compressor surge limit, some of that flow must be vented or recycled to the inlet to stay above surge.

In process operations, there are instances where ratio control is required to maintain a consistent blend of two or more components. This control action is used in chemical, food & beverage, and pharmaceutical batching operations.

YS100 series instruments are stand alone devices that control or indicate process variables throughout a manufacturing plant. RS485 communications cards can be optionally provided to transfer data from each instrument digitally to a PC-based operators station. Below is a typical system configuration to transfer data bi-directionally through this communications bus.

The boiler combustion control system is designed to maintain a proper air/fuel mixture under varying load conditions and within safe limits. The system should provide nearly complete fuel combustion as efficiently as possible. Discussions here are limited to oil and/or natural gas fired industrial boilers. 

Automated control of industrial boilers is an excellent application for YS1700 microprocessor-based loop controllers. These instruments can be programmed to perform the operations of plant master, boiler master, fuel and air control with oxygen trim and drum level/feedwater control.

Steam drum level control is necessary to add makeup water as steam is delivered into the header and to the associated process equipment. The system should control the drum level at a specific set point while compensating for varying steam demands and drum pressures. For a given volume of steam and blowdown leaving the steam drum, an equal amount of water should replace that inventory.

Yokogawa enjoyed strong sales of its line of YS80 instruments from their inception in 1980 to discontinuation in 2008. Thousands of the SLCD (single loop controller) and SLPC (programmable controller) where sold in the United States. As parts began to become scarce, the next generation of high-end controller was designed and released as the YS100 series.

In process control it is not uncommon for systems to be affected by dead times, due to material transfer times. This is evident typically in pipelines. A fluid of density ρ and flow rate w in a section of pipe A the length of d takes the amount of time τ = ρAd/w to cover the whole distance (see Figure 1).