SPECIFICATIONS

• Default trigger condition: Peak Ground Acceleration (PGA) on any Axis. settable range: 0.005g to 1.7g
• Features: Fail safe design, Online testability, manual and automatic self test
• 3 dB Cut-off frequency on each axis: 13.5 Hz
• Output: Two numbers of Potential free 2 form C (DPDT) relays with contact rating of 1.0A at 24VDC - Earth quake relay and status relay
• Battery: Lithium-ion battery. 3700mAH X2(10Hrs Backup) Automatic charging during main power operation
• Calibration: Generally not required. Tilt table can be used for verifying the calibration
• Enclosure and mounting: Rugged IP 66, 4 M8 mounting holes for easy installation
• Operating Temperature: 0-70 Degree Celsius
• EMI/EMC: Designed to meet IEC-61000-4.2, 4.3, 4.4 ,4.5,4.6 and 4.8  (to be tested)
• Chip software: MISRA-C 2006 Complaint. (Verification Under Progress)
• MTTF:  >80 Years (As per MIL-HDBK-217PLUS)
• Software features: remote reset for automatic leveling, self test, password protected access, saving instrument details in EEPROM, setting trip parameters, display of battery status, real-time plots of accelerations and display of various other system parameters such as voltage and temperature

APPLICATIONS

• Primarily designed for Automatic Reactor Trip System (ASTS).
• Can also be used for Industrial Processes, Chemical Processes, Gas valves, Hazardous Systems, Solenoids, Elevators, Walkways, Electronic gates and door.

BARC Seismic Switch (Digital) is packed with many distinctive features specially designed for meeting the standards for nuclear industries. This can be helpful in highly accurate detection of a strong earthquake or a structural vibration with various safe shut down options. This has a broad range of applications such as Industrial Processes, Chemical Processes, Gas Valves, Hazardous Systems, Solenoids, elevators, walkways, Electronic gates and doors.

Seismic Switch (Digital) monitors its attachment point to detect seismic (earthquake) motions in all 3 mutually perpendicular axes(X, Y and Z). It monitors acceleration in all the three axes and triggers on detection of Peak Ground Acceleration (PGA) on any axis. The unit provides two numbers of 2 Form C (DPDT) isolated relay contacts. Relay 1 (Earth quake relay) and Relay 2 (Status relay). Coils of both these relays are in energised state during normal operation and de-energises on any fault. This ensures 'fail safe' operation of the system. On-line testability is another important feature in this system which enables the user to manually initiate the self-diagnostics of the system without removing it from the installation. Seismic Switch (Digital) can communicate to a Graphical User Interface Software through an RS-485/RS-232 link. Various features of this software include remote reset for automatic leveling, self test, password protected access, saving instrument details in EEPROM, setting trip parameters, display of battery status, real-time plots of accelerations and display of various other system parameters such as voltage and temperature.  The system can be programmed for having additional triggering conditions such as Cumulative Average Velocity (CAV).

SPECIFICATIONS

Table 1 Specifications of Digital Seismic Switch.

Sr. No	Specifications	Value
1.	Actuation Methods	Peak Ground Acceleration (PGA) on any Axis. Default 0.1g on each axis  0.005g to 1.7g with a set point accuracy of 0.005g. The set point can be fixed through RS-232 /RS-485interface.  Standardized Cumulative Average Velocity (CAV) Default CAV Threshold (0.025g ) and Trip on 0.16 g-sec
2.	3 dB Cut-off frequency on each axis	13.5 Hz
3.	Output	Two numbers of Potential free form C relays with contact rating of 1.0A at 24VDC. Earth quake relay and status relay. Relay actuation conditions is given in the table 1.
4.	Closure Timing	On seismic event, relay will remain actuated for user settable time period. Typically set for 5 Seconds.
5.	Battery	Lithium-ion battery. 3700mAH X2  (10Hrs Backup)
6.	Battery Charging	Battery will be charging while system is operated on mains power. Automatic switching to battery during power outage
7.	Enclosure	IP 66
8.	Operating Temperature	0-70 Degree Celsius
9.	Calibration	Generally not required. Tilt table can be used for verifying the calibration
10.	EMI/EMC	As Per IEC-61000-4.2, 4.3, 4.4 ,4.5,4.6 and 4.8  (to be tested)
11.	Functional verification on Shake Table	Yes
12.	Warning conditions	Over temperature; Power supply errors, Flash memory checks and  Battery Charging error  through status relay. RS-232 /RS-485 communication can be used for detailed diagnosis
13.	Chip software	MISRA-C 2006 Complaint. (Verification Under Progress)
14.	GUI Software	Settings to EEPROM  Real time Plot and Data Storage  Self test command Password protected access
15.	MTTF	>80 Years (As per MIL-HDBK-217PLUS)

Table 2 Various Triggering conditions of Digital Seismic Switch.

Condition	Earthquake Relay	Status Relay
Earth quake	Actuates for 5 seconds	No Actuation
Complete power loss including battery	Actuates and latches till power restores	Actuates
Manual  confidence test	Actuates for 5 seconds	Actuates for 5 seconds
Working on battery	No actuation. It will actuate on detection of earth quake	Actuates when battery power is less than 98%
Automatic confidence test pass	No actuation	Actuates for one second
Automatic confidence test fail	Actuates	Actuates
Warning condition	No actuation	Repeated actuation in 2 seconds interval

APPLICATIONS

BARC Seismic Switch (Digital) is packed with many distinctive features specially designed for meeting the standards for nuclear industries. It can be helpful in highly accurate detection of a strong earthquake or a structural vibration with various safe shut down options. This has a broad range of applications such as Industrial Processes, Chemical Processes, Gas Valves, Hazardous Systems, Solenoids, elevators, walkways, Electronic gates and doors.

After Fukushima incident it has become a regulatory requirement to have Automatic Reactor Trip System (ASTS) on detection of earthquake. This is designed to scram the reactor upon the occurrence of a seismic event, before turbine trip or other conditions resulting from the seismic disturbance could cause a scram. The earlier scram could give a lead time between 5 to 20 seconds. The lead time could provide resulting benefits such as reduced loads during the seismic event and, therefore, fewer burdens on the plant systems. It may also reduce the likelihood of a LOCA or severe transient after a seismic event. ASTS comes under classification as safety Class IA system (reactor protection) and has to meet the relevant standard requirements such as on-line testability, fail safe and other qualification requirements. Since systems that are available in the market and not meeting these requirements, BARC has developed fully functional prototype designs of the Seismic Switch.

FACILITIES REQUIRED / INFRASTRUCTURE REQUIREMENT FOR COMMERCIAL PRODUCTION

• Standard Electronics PCB assembly and testing instruments such as Soldering station, multi-meters and an Oscilloscope.
• Windows 7 Desktop/Laptop installed with GUI software of the Seismic Switch.  There should be RS-232 and RS-485 communication ports available in the PC.

An Instrumentation/Electronics/ Electrical engineer who is familiar various qualification procedures of this system.