GENERAL
.1 Controls Power Supplies
The electrical and control systems shall be designed such that the failure of any one power supply shall not prevent the continued operation of operationally independent control groups
other than that in which the failure occurs, and that failure of automatic control power supplies does not prevent manual control. As a minimum, each MCC shall include separately fused
power supplies for:
• MCS hardware
• MCC control circuitry, sub-fused for each of: – individual drive control circuitry – common indicating light press to test circuitry
.2 Fan/Pump Proving
Where fan or pump proving is specified, the proving device shall be wired in series with the motor starter auxiliary contact, such that the status input to the MCS is a combination of starter
closing and device proving.
Fan/pump proving shall be by fan/pump differential pressure switch, motor current switch, or, where variable speed driven, proprietary VSD current switch output if available.
For VSD driven motors, select and set the pressure or current switch to avoid erroneous tripping at the lowest anticipated motor speed.
Program the MCS to wait an adequate time after motor start for proving contact to make, before registering as a fault. After first fault, attempt two more motor starts. If proving contact fails to make after the third attempt, latch fault and register alarm.
.3 Motorised Dampers
Motorised dampers shall have failsafe condition, hard wired fan interlocks, fire resistant control cabling and be wired from the appropriate MCC.
Where damper/fan interlocks are specified above, the damper shall be electrically interlocked with the respective fan. Interlocks shall be such that the damper responds to the associated
fan’s automatic and manual commands, as well as closing on fan fault.This requires the damper actuator to be wired direct from the MCC as indicated by Note 1 above, with interposing relays, rather than being controlled by the MCS with a software interlock. Inputting MOA signals to the MCS does not provide manual control facility in event of MCS failure.
Interlocked dampers shall be closed when respective fan is off.
Program MCS to wait an adequate time after motor start for damper position switch to make, before registering as a fault. After first fault, attempt two more motor starts. If damper switch
fails to make after the third attempt, latch fault and register alarm.
Where the fan and damper sizes/characteristics are such that starting the fan against a closed damper could result in excessive pressure, turbulence, or opening torque on the damper, and
therefore compromise damper life and/or operation, provide the following starting features:
• Fans with VSDs: Program VSD to ramp start the fan in parallel with damper opening.
• Fan is direct on line or star/delta started: Provide fan delay on timer, to allow damper to partially open before fan start, provided the likely frequency of fan starts is sufficiently low such the increased electrical and mechanical stress on the motor during start (due to fan back-winding at end of the start time delay) does not cause significant reduction in fan/motor life expectancy. If fan start frequency is such that reduced life expectancy is significant, either ensure motorised damper is sufficiently robust and durable to withstand fan stall pressure and operate in the turbulent conditions generated by the fan during startup/opening, or provide electromechanical fan braking.
Motorised damper position switches shall be provided as indicated in the MCS POINTS SCHEDULE. They shall be normally open, set to close when damper is powered away from its failsafe condition, such that loss of signal when damper is required to return to failsafe shall cause an alarm.
.4 Dual Purpose Smoke Extract/Spill Air Fans
Where dual purpose smoke extract/spill air fans are required to have thermistor motor protection (refer ELECTRICAL FOR MECHANICAL – MOTORS), provide MCS fire mode outputs and hard wired relays to isolate the thermistor protection when the fan is required to operate in smoke extract mode. Dedicated smoke extract fans do not require thermistor protection (and if provided, shall not be connected).
.5 Status and Fault Inputs to MCS
Where status input to the MCS is specified in the MCS POINTS SCHEDULE, the MCS shall log appropriately worded alarm messages, as indicated below, when the status input differs from the control output.
.6 MCC Alarm
Provide a visual alarm (red flashing light) at each MCC that supplies:
• Any fire fan (a fan that is required to run in fire mode) with local MCC On/Off/Auto switch control. This excludes dedicated fire fans that have FFCP Test/Off/Auto switches but no
MCC On/Off/Auto switches, e.g. stairwell pressurisation fans.
• Any other fan that supplies or extracts at least 1000 l/s to/from any one fire cell, and that is required to shut down in fire mode.
The visual alarm shall be activated whenever any of the above fans’ MCC On/Off/Auto switches are set to either OFF or ON.
These MCC alarms shall be inputted to the MCS and repeated at the Operator Workstation.
.7 Control Valves
All CHW control valves shall be closed when corresponding fan is off.
MVAC START/STOP CONTROL
MVAC automatic operation shall be initiated by independent MCS time schedule, optimised start, and after-hours air conditioning programmes as listed below.
After-hours shall be activated via a suitable after hours graphic at the operator workstation.
The MCS shall provide staged starting of mechanical services plant on morning start-up and on restoration of power after a power failure, to minimise starting currents.
TOILET VENTILATION FANS
Extract fans shall run continuously under time clock control and monitored and controlled by the MCS.
STAIRCASE PRESSURISATION FANS
.1 General
System shall be initiated by smoke zone inputs
.2 Apartment
A differential pressure sensor and controller shall measure pressure difference between stairwell and reference point (typical floor corridor) and modulate the fan variable speed drive
to control the stair pressure between 25 Pa and 50 Pa under varying door open conditions.
Pressure controller and variable speed drive shall be quick acting with adjustable PID capable of controlling stairwell pressure within a range of 25 Pa and restoring stairwell pressure within
10 seconds of doors opening and closing.
GENERAL EXHAUST/SUPPLY FANS
Fans shall run continuously under time clock control and monitored and controlled by MCS including sewage treatment plant, water treatment plant and water storage tanks.
OUTDOOR AIR SUPPLY FANS
The outdoor air supply fans shall run continuously under time clock control and monitored and controlled by the MCS.
SPLIT UNIT
.1 Lift Machine Rooms
Systems shall be enabled 24-hours/day.
Each unit shall have room air temperature sensor. The initial set point shall be 30° C with adjustable range 20 to 35 ° C.
Control I/O cabling outside LMR fire cells shall be fire rated.
Standby FCUs shall be initiated by any one of:
• Duty unit fault or manual off,
• High temperature warning (initial set point shall be 37.° C) Alarm signal shall be raised at the Operator Workstation
STP VENTILATION
Fan operation shall be continuous, manually controlled from MCC On/Off push buttons.
PLANTROOM VENTILATION
All plantroom fans (supply and extract) shall be controlled by a space temperature sensor and monitored by the MCS through a variable speed drive to limit the space temperature to a preset maximum. Minimum airflow shall be set to 50% design airflow. Supply and extract fans shall be interlocked for each plantroom to maintain a positive differential.
FIRE PUMP ROOM VENTILATION
Fire Pump Room fans shall start under fire alarm signal.
CARPARK VENTILATION (CO SENSOR)
The MCS shall monitor the CO levels in all zones from CO sensors located on the car park walls and columns at a height of 1200mm AFFL. Operation of the supply and extract fans shall be in pairs (duty assist configuration) on a floor by floor basis.
The high/low speed of Jet fans shall be automatically selected based on CO levels. Increasing average CO shall initiate a step-up in fan speed. (To avoid hunting the fan speed shall also
only be modified every 5 minutes).
The car park ventilation system shall incorporate carbon monoxide monitoring and variable speed drive of carpark fans and dampers based on the worst case of CO sensors distributed around each car park level.
SWITCHROOM AIR CONDITIONING
The system comprises of mechanical ventilation and FCUs cooling. All fans and FCUs shall be controlled by a space temperature sensor and monitored by a MCS through a variable speed
drive to limit the space temperature to a preset maximum. Extract and supply fans shall be hardwired interlocked.
Initial control settings shall be:
Alarm signal shall be raised at the Operator Workstation. MCS connection shall be to nearest DPU.
TRANSFORMER ROOM VENTILATION
The system comprises of mechanical ventilation or FCUs cooling. All fans and FCUs shall be controlled by a space temperature sensor and monitored by a MCS through. Initial control settings shall be:
Alarm 37ºC 34ºC Alarm signal shall be raised at the Operator Workstation. MCS connection shall be to nearest Ground Level DPU.
ESCALATOR LOBBY AIR CONDITIONING
The systems comprise fan coil units with cooling.
Provide modulating cooling control via modulation of chilled water control valve to maintain supply air temperature setpoint. Cooling control shall be cascade type from one room temperature sensors per FCU with supply air temperature feedback from a duct mounted sensor. Supply air temperature shall be reset from minimum to maximum across 0-100% of cooling control ranges respectively.
Room temperature sensors shall generally be mounted on columns or walls in locations coordinated with the fitout design. The units shall be under time clock control and monitored by MCS.
GENERATOR PLANTROOM VENTILATION
Generator plantroom ventilation systems are provided. The system comprises of mechanical ventilation fans, operating in conjunction with generators and their integral exhaust fans. Supply air fans shall be controlled and monitored by the MCS, such that as each generator is enabled (and the associated generator exhaust fan is enabled) the associated supply air fan is also enabled. Supply and Extract fans (Extract fans by generator contractor) shall be hardwired interlocked, and shall operate simultaneously.
Flow proving and high temperature alarm signals shall be monitored and raised at the Operator Workstation. MCS connection shall be to nearest DPU. Liaise with the generator contractor for interface requirements.
LIFE SAFETY SYSTEMS
.1 General
The Fire Alarm System will provide the relevant smoke control signals at each MCC. MCC fan control circuits shall include fire alarm relays as necessary to activate specified fan an damper
control functions on receipt of the relevant smoke alarm from the Fire Alarm System.
Smoke detectors shall shut down a smoke affected supply fan or air handling unit fan, operate motorised dampers accordingly and initiate alarm at MCS operator workstation.
MCS shall shut down fans as required prior to starting fire fans. Starting of fans under fire mode and after system reset shall be staggered
Staircase pressurisation fans shall only run when initiated by Fire Alarm System.
Other fan run outputs other than stairwell pressurisation fans shall take account of manual starting and stopping of fans via MCC on/off/auto switch.. A smoke control mode ‘run’ output
shall not override a local on/off/auto switch ‘off’ command. A smoke control mode ‘off’ output shall override a local on/off/auto ‘on’ command (as sensed by contactor status feedback
compared to MCS command output just prior to fire event). MCS Electrical for Mechanical interfacing shall be designed to achieve the above.
Fan fault outputs shall be from differential pressure switches across fan, input to the MCS. Pressure setpoint and differential shall be adjustable. Initial setpoint shall be 40% of the fan
duty pressure.
The MCS shall be programmed to reset life safety systems via, either
• Receipt of smoke zone ‘Off’ command followed by cancelling of ‘Off’ command and absence of ‘Run’ command (i.e switching of the on/off/auto from Off to Auto after cancellation of the smoke alarm).
• Individual zone or global manual reset command via MCS operator workstation.
• Or Portable Lap Top PC, subject to absence of smoke zone ‘Run’ command.
Air handling system smoke detectors are required to be located at the natural collection points for hot smoke, with due regard to duct geometry. Coordinate with and assist fire alarm trade.
When fire is detected in multiple smoke zones the control outputs shall be prioritised to a preprogrammed sequence.
Smoke detectors are required to be located at the downstream ducts of carpark supply fans and all outdoor air supply fans.
The air handling system and outdoor air system smoke detectors shall be installed by the Fire Alarm Trade and connected to the Fire Alarm System.
.2 Fan Proving
Provide fan proving on the following fans:
• Smoke Extract Fans
• Dual Purpose Spill/Smoke Extract Fans
• Carpark Ventilation Fans
• Kitchen Extract Fans
• Generator Room Ventilation Fans
The relevant MCS fan “Fault” output to the FAS shall be initiated by:
• Lack of fan run input, or
• Fan fault input (motor overload), or
• Corresponding motorised damper failure to open (as indicated by damper position switch).