Doc: ps2001-5-1101-001 Rev: R02. 00
Safety systems and interlocks
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1486357009-URS, URS
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| Safety systems and interlocks (8) Safety system modules will be provided that can detect emergency stop conditions and ensure that the associated devices are switched to a safe state, overriding all other commands from the system. (9) The safety system modules will ensure that the state of an affected device will match the hardwired state of the device (for example, if the system requires a drive to run for normal process reasons, but the safety system has physically removed power from the drive, the safety system module will detect this and stop the drive, following the true state imposed upon the drive. (10) Safety system modules must be able to distinguish between separate safety zones. (11) Safety system modules will be configurable to allow software latching and reset as well as detecting hardwired latching and reset of a safety signal. (12) Interlock handling modules will be provided for the following types of interlock 1 Interlock: a simple interlock that is active whenever a set of events is true, it will force any associated devices to a safe state 2 Permissive: takes no action if a device is in a non-safe state, but once the device is in a safe state will prevent a transition to anon- safe state (i.e. will not force a valve to close, but once it is closed, will prevent it from reopening) 3 Trip: a latching interlock, it activates whenever a set of events are true (like an interlock, but will not deactivate until the triggering conditions are removed and a reset signal has been given (effectively a latching interlock, it will force any associated devices to a safe state and it will remain in that state until reset 42-71 Doc PS Rev Rb Mathematical calculations (13) Calculation modules will be provided to carryout various common mathematical engineering functions (these will be in addition to the standard mathematical functions that are built into the Controller trigonometric functions, exponentials, logarithms, c. These will include, but not be limited to • Rolling average calculation (multiple samples and variable sample intervals) • Cumulative average calculation • Weighted moving average calculation • Exponential moving average calculation • Calculate the rate of change of a signal • Calculate the integral of signal with respect to time • Convert a percentage value to variable mark/space square wave • Convert a running pulse train to anon off state • Ramp generator (variable direction, variable intervals and variable increment size) • Sawtooth wave generator (variable frequency and amplitude) • Triangular wave generator (variable frequency and amplitude) • Sinewave generator (variable frequency and amplitude) • Square wave generator (variable frequency, mark/space ratio and amplitude) Doc PS Rev R 43-71 (14) In addition to the mathematical calculations, there will be some timed calculations for pulse generation (in which each pulse is activated in turn fora specified time period, all of these will have variable pulse lengths and repeating or single shot modes • Dual state pulse generator (2 state) • Quad state pulse generator (4 state) • Octa state pulse generator (8 state) • Hexadeca state pulse generator (16 state) Download 1.5 Mb. Share with your friends:
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