Toshiba GR-200 Series Instruction Manual

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6F2T0200 (0.15)GRE200 (1,2)- 490 -Software interlock function (ILK)Devices must be controlled in accordance with the prevailing operational condition of theelectric power system. If a device does not act or behave in accordance with the operationalcircumstances, inappropriate device control can result in outages or fatal incidents for thenetwork. In order to avoid such circumstances, a software interlock (ILK) function is providedthat is able to examine the current operational situation and determine whether to permit thecontrol of a particular device.When using the ILK function, an interlock-check formula is required. The interlock-checkformula examines the operational conditions for all devices, and is stored in the ILK database.The ILK function provides an output signal “OK/NG decision information”; the “OK/NGdecision information” is transferred to the control functions†, which control the externaldevices. Following which, the control functions can commence with the control of the selecteddevices in response to the respective “OK/NG decision information”.Prior to controlling a device, the interlock-check function is used to determine whether thecontrol of a device is correct or not. If the interlock-check finds that the conditions for devicecontrol have not been satisfied in accordance with the appropriate interlock condition, controlof the device is forbidden. Figure 4.2-1 provides an overview of the interlock-check process.Formulae for interlock-check are stored in an ILK database; these formulae are used in orderto enable the interlock-check function to output a decision. If the proposed operation of aparticular device is deemed correct then an “OK-decision” is determined by the formulae, anddevice control is allowed. However, if the proposed operation of the device is deemed incorrectthen an “NG-decision” is determined by the formulae, and device control is not allowed.