Purpose of industrial seismic protection system (ISPS) is a continuous monitoring of seismic influences on reactor and generation of emergency protection (EP) signal for reactor trip in case if seismic influence reaches the level of the assigned setpoint.
ISPS consists of two independent three-channel sets.
The composition of each ISPS set includes the following:
- Three seismic sensors SD4. SD4 are sensors, implemented on the basis of 3D meter of vibration parameters, which are intended for measuring the low-frequency vibrations of NPP construction elements with amplitude of ± 1g in the frequency range from 0 to 50 Hz. SD4 performs the following functions:
- provision of continuous monitoring of seismic influences on reactor plant of nuclear power plant;
- generation of discrete emergency signal on exceeding of the set level of seismic influence;
- generation of discrete signal on the start of registration;
- generation of discrete signal of seismic sensor good condition;
- generation of separate analogue signals (4-20 mA) by axes Х, Y, Z;
- generation of generalized analogue signal (4-20 mA), proportional to the absolute value of seismic influence vector.
- Three commutation units. The type of unit and its functions depend on specific project of control and protection system (CPS-CSS). The commutation unit ensures (depending on a project) the following functions:
- сommutation and galvanic separation of signals received from SD4 to be transferred to various CPS-CSS equipment;
- multiplication of discrete emergency signals on exceeding of the set level thresholds of seismic influence;
- сonversion of signals to be transferred via serial interface.
Instead of commutation units every set of ISPS could be completed with data acquisition and processing device (DAPD) cabinet which ensures necessary galvanic separation and logical processing of signals from SD4, displaying, archiving, alarm signaling, generation of generalized EP signal, majority voting according to logic 2 out of 3.