2.6.20
System Architecture
System shall be designed in modular fashion.
Provide spare capacity of the
following:
a.
Input, digital- 25 percent.
b.
Input, analog - 25 percent.
c.
Controller memory - 25 percent spare.
d.
Output digital - 10 percent.
e.
Output analog - 10 percent.
2.6.20.1
Inputs
CMS controller shall be capable of accepting inputs as described below:
a.
Analog Inputs (AI): Analog inputs originating from sensing
elements shall be monitored and buffered as AI, except that
automatic conversion to proper engineering units shall occur
without any additional signal conditioning as follows:
1. Temperature inputs from thermistors or RTDs or temperature
transmitters shall be converted to degree C,
2. Flow inputs from flow transmitters shall be converted to liter
per minute, cubic meter per minute or as specified in process and
instrumentation diagram.
3. Valve or damper position from potentiometer or similar device
shall be converted to percent open.
4. Pressure input from pressure transmitter shall be converted to
mm of water kPa as specified in process and instrumentation
diagram.
b.
Discrete Inputs: CMS controller shall accept discrete signal from
device such as contactor, relay, limit switch, pressure switch,
and temperature switch. Input shall be device capable of
withstanding continuous shorting to 120 V ac or to 1500 volts for
fifty (50) microseconds.
2.6.20.2
Outputs
Controllers shall be capable of directing outputs as follows:
a.
Analog Outputs (AO): Analog outputs as direct or reverse function
of associated analog inputs shall modulate final elements in
response to controller algorithms. Final element actuators shall
be industrial grade capable of accepting a modulated [electronic]
[pneumatic] signal from the controller [via a signal converter,
current to pneumatic]. Electronic signal shall be 4-20 mA dc with
a minimum of 16 [_____] bit resolution. [The pneumatic signal
shall be 21 to 34 kPa 3 to 15 psi. Each pneumatic output shall
have feedback for monitoring of the actual pneumatic signal.]
b.
Digital Outputs (DO):
Digital outputs shall command equipment to
SECTION 15561A
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