Orange County NC Website
Browse       Search
ORANGE COUNTY 230923-8 <br /> <br />Emergency Management Warehouse Building Dehumidification Extension of Existing Direct Digital <br /> Control System for HVAC <br /> <br />Maximum response time of 10 nanoseconds. 1 <br /> 2 <br />Minimum transverse-mode noise attenuation of 65 dB. 3 <br /> 4 <br />Minimum common-mode noise attenuation of 150 dB at 40 to 100 Hz. 5 <br /> 6 <br />Diagnostic Devices: Each CU shall be supplied with connections to which Owner’s maintenance personnel can 7 <br />connect portable diagnostic operator’s terminals (PDOTs) for data display, setpoint modification, and reloading 8 <br />and modification of controller programs. 9 <br /> 10 <br />Spare Equipment: Provide spare control unit boards and spare I/O boards as required. It shall be possible for 11 <br />trained Owner personnel to replace CU boards and load software via a workstation or PDOT: 12 <br /> 13 <br />Provide two spare control unit boards. If power supplies are separate, supply separate power supplies 14 <br />and other parts to make at least two complete sets of DDC control equipment spares. 15 <br /> 16 <br />If I/O boards are separate from the CU boards, provide four spare I/O boards for each spare CU board 17 <br />provided above. 18 <br /> 19 <br />Control Functions: All control functions shall execute within the standalone control units via DDC algorithms. The 20 <br />operator shall be able to customize control strategies and sequences of operations defining the appropriate 21 <br />control loop algorithms and choosing the optimum loop parameters. Each CU shall include the following 22 <br />standalone functions: 23 <br /> 24 <br />Direct Digital Control algorithms and control sequences are to be CU resident and be capable of 25 <br />standalone operation. All DDC programs shall be custom written as required to meet the performance 26 <br />criteria spelled out in the sequence of operation paragraphs for each controlled mechanical system. 27 <br />PID control mode shall be employed as appropriate to the application and per sequences or operation. 28 <br /> 29 <br />Enable/Disable: All CU resident DDC programs shall be capable of being enabled or disabled from any 30 <br />workstation. In the enable mode all DDC loops shall be active and output signals shall be routed to the 31 <br />final control elements. In the disable mode all DDC loop calculations shall continue but outputs to 32 <br />actuators shall be suppressed. (When disabled, control outputs shall stay in the same state or position 33 <br />as commanded from the central or until they are manually set to automatic.) 34 <br /> 35 <br />Integral Windup Prevention: To eliminate integral windup, all PID programs shall automatically invoke 36 <br />integral windup prevention routines whenever the controlled unit is off, under manual control or under 37 <br />control of an system or time initiated program, or when the controlled unit is in the process or starting or 38 <br />stopping. 39 <br /> 40 <br />Default Value Operation: All CUs shall be capable of being programmed to utilize stored default values for 41 <br />assured fail-safe operation of critical processes. Default values shall be invoked upon sensor failure or, if the 42 <br />primary value is normally provided by the central or another CU, by loss of bus communication. Individual 43 <br />application software packages shall be structured to assume a fail-safe condition upon loss of input sensors. 44 <br />Loss of an input sensor shall result in output of a sensor-failed message at the central control and command 45 <br />station. Each CU shall have capability for local readouts of all functions. 46 <br /> 47 <br /> 48 <br />APPLICATION SOFTWARE 49 <br /> 50 <br />Provide the following programs in addition to control algorithms defined on the drawings: 51 <br /> 52 <br />Scheduling: Provide a calendar format for annual time-of-day scheduling for equipment operation, trending, 53 <br />logging and reports, etc. Provide the following minimum features: 54 <br /> 55 <br />Day-type schedules (Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday, Holiday, 56 <br />Pre-Holiday day, Vacation day, Special Day, etc., 24 hours per day) 57 <br /> 58 <br />Monthly schedules (allow individual assignment of day types to each day of the month). 59 <br /> 60 <br />DocuSign Envelope ID: 7668B866-6C26-485C-9A45-DAAB5D4BD951