Bryant F Bedienungsanleitung PDF herunterladen (Seite 68)

When free cooling is available as determined by the

appropria te changeover command (dry bulb, outdoor

enthalpy, differential dry bulb or differential enthalpy), a

call for cooling (Y1 closes at the thermostat) will cause

the economiz er control to modulate the dampers open and

closed to maintain the unit supply air temperature at 50 to

55_F. Compressor will not run.

During free cooling operation, a supply air temperature

(SAT) above 50_F will cause the dampers t o modulate

between Minimum Position setpoint and 100% open. With

SAT from 50_Fto45_F, the dampers will maintain at the

Minimum Position setting. With SAT below 45_F, the

outside air dampers will be closed. When SAT rises to

48_F, the dampers will re-open to Minimum Position

setting.

Should 100% outside air not be capable of satisfying the

space temperature, space temperature will rise until Y2 is

closed. The economizer control will call for compressor

operat ion. Dampers wil l modulate to maintain SAT at 50

to 55_F concurrent with Compressor 1 operation. The

Low Ambient Lockout Thermostat will block compressor

operation with economizer operation below 42_F outside

air temperature.

When space temperature demand is satisfied (thermostat

Y1 opens), the dampers will return to Minimum Damper

position if indoor fan is running or fully closed if fan i s

off.

If accessory power exhaust is installed, the power exhaust

fan motors will be energized by the economizer control as

the dampers open above the PE-On setpoint and will be

de--energized as the dampers close below the PE-On

setpoint.

Damper movem ent from full closed to full open (or vice

versa) will take between 1-1/2 and 2-1/2 minutes.

Heating With EconoMi$er IV

During Occupied mode operation, i ndoor fan operation

will be accompanied by economizer dampers moving to

Minimum Position setpoint for ventilation. If indoor fan is

off, dampers will close. During Unoccupied mode

operation, dampers will remain closed unless a DCV

demand is received.

When the room temperature calls for heat (W1 closes), the

heating controls are energized as described in Heat ing,

Unit Without Economizer above .

Demand Controlled Ventilation

If a field-installed CO

sensor is connected to the

Economize IV control, a Demand Controlled Ventilation

strategy will operate automatically. As the CO2 level in

the space increases above the setpoint (on the EconoMi$er

IV controller), the minimum position of the dampers will

be increa sed proportionally, until the Maximum

Ventilation setting is reached. As the space CO

leve l

decreases because of the increase in fresh air, the

outdoor-damper will follow the higher demand condition

from the DCV mode or from the free-cooling mode.

DCV operation is available in Occupied and Unoccupied

periods with EconoMi$er IV. However, a cont rol

modification will be required on the 580J unit to

implement the Unoccupied period function.

Supplemental Controls

Compressor Lockout Rel ay (CLO) -- T he CLO is a vaila ble

as a factory-installed option or as a field --installed

accessory. Each compressor has a CLO. The CLO

compares the demand for compressor operation (via a

24-v input from Y at CLO termina l 2) to operation of the

compressor (determined via compressor current signa l

input at the CLO’s current transformer loop); if the

compressor current signal is lost whil e the demand input

still exists, the CLO will trip open and prevent the

compressor from restarting until the CLO has been

manually reset. In the lockout condition, 24-v will be

available at terminal X. Reset is accomplished by

removing the input signal at terminal 2; open the

thermostat briefly or cycle the main power to the unit.

Phase Monitor Relay (PMR) -- The PMR protects the unit

in the eve nt of a loss of a phase or a reversal of power line

phase in the three--pha se unit power supply. In normal

operation, the relay K1 is energized (contact set closed)

and red LED indicator is on steady. If the PMR detects a

loss of a phase or a phase sequence reversal, the rela y K1

is energized, its contact set is opened and unit operation is

stopped; red LED indic ator will blink during lockout

condition. Reset of t he PMR is automatic when all phases

are restored and phase sequence is correct. If no 24--v

control power is available to the PMR, the red LED will

be off. Smoke Detectors -- Factory--installed smoke

detectors are discussed in detail starting on page 17.

RTU--MP Sequence of Operation

The RTU--MP will control the compressor, economizer

and heating outputs based on its own space temperature

input and setpoints. An optional CO

IAQ sensor mounted

in the space can influence the economizer minimum

position. The RTU--MP has its own hardware clock that is

set automatically when the software is installed on the

board. The RTU--MP’s default is to control to occupied

setpoints all the time, until a type of occupancy control is

set. Occupancy types are described in the scheduling

section. The following sections de scribe the operation for

the functions of the RTU--MP. All point objects that are

referre d to in this sequence wil l be in reference to the

objec ts as viewed in BACview

Handheld.

580J

1 2 ... 63 64 65 66 67 68 69 70 71 72 73 ... 84 85

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