Process parameters protection equipment (PPPE) is intended for:
- receipt and conversion of analogue signals from sensors of process parameters monitoring;
- calculation of current values of parameters monitored;
- comparison of monitored parameters’ current values with the setpoints, and generation of discrete signals of exceeding the setpoints by parameters’ values;
- transfer of discrete signals on setpoints exceeding into signal logical processing equipment (SLPE);
- multiplication of signals from sensors of state of main technological equipment (MTE), and their transfer to SLPE;
- transfer of discrete signals, characterizing PPPE state (good condition and output to check mode), to equipment of typical software-hardware means (TSHM);
- transfer of all generated signals via gateway to SLPE and top level system of Unit (TLS-U).
In compliance with classification of NP-001 (OPB 88/97) by influence on safety PPPE is related to elements of control safety system - class 2 (2NU). In compliance with NP-026-04 PPPE is related to functional group 2UK2.
PPPE ensures the following:
- receipt of analogue signals from process parameters sensors – thermo-electrical converters (TEC) and resistance temperature detectors (RTD);
- receipt of discrete signals from sensors of state of safety system technological equipment;
- automatic introduction of corrections (compensation) for temperature of TEC “cold junctions” by signals from RTD;
- linearization of TEC characteristics within the range from 0 to + 400 °С;
- calculation of complex parameters – departure from nucleate boiling in the primary circuit and difference of saturation temperature values;
- taking into account the values of hydrostatic columns at measuring the values of pressure and levels;
- possibility of changing the time constant of input signal meter;
- supply of UCS sensors;
- setting of protection setpoints by every parameter being monitored;
- comparison of current values of monitored parameters with the setpoints, and generation of discrete signals of the safety system (SS) actuation at parameter values exceeding the setpoints;
- zone of return (hysteresis) within the range from 1 to 4 % of upper limit of measuring range of parameter by which the discrete signal is generated;
- transfer to SLPE of the generated actuation signals at monitored parameters reaching the assigned values of setpoints, at break of communication lines, absence of electric supply; receipt, multiplication and transfer to SLPE of discrete signals on state of SS technological equipment;
- transfer to TPTS of analogue signals characterizing the current values of individual process parameters being monitored;
- automatic monitoring of intrinsic good condition.
Main reduced error of generating and transferring the analogue signals is within the limits of ±0.3 %.
PPPE generates and transfers to TPTS the following discrete signals:
- intrinsic good condition of channel;
- channel output to check mode.
PPPE ensures the indication in channels, and transfer to SLPE gateway via Ethernet of the following information:
- current values of process parameters being monitored;
- values of actuation setpoints;
- good condition signal;
- signal on output to check mode and on opening of channel doors.
The monitoring is performed along the whole circuit from sensors’ outputs to output elements of threshold module. Signal of failure is generated in the following cases:
- at break of sensors’ communication lines;
- at absence of sensors supply;
- at sensors’ signals leaving the assigned limits (invalidity of signal);
- at absence of functional modules at the routine places;
- at disturbance of functional modules’ operability.