Carrier 50EJQ Información técnica descargar pdf (Pagina 11)

Time Guard Override may also be initiated from CCN by

setting TGO option in SERVICE table from OFF to ON.

The random 1 to 63 seconds is also applied to the indoor-

fan motor on power up, only.

Economizer Operation (VAV, CV, and Heat Pump

with CCN Sensors) —

The economizer dampers will

open to provide free cooling and/or air quality control when

the outside conditions are suitable. It is accomplished by con-

trolling supply-air temperature to a certain level determined

by the Economizer Submaster Reference (ECONSR).Air qual-

ity control is driven by the IQMP (indoor-air quality mini-

mum position) calculated by the IAQ algorithm. The IQMP

will increase as the need for fresh air becomes greater. This

algorithm will calculate the submaster reference tempera-

ture ECONSR based on atmospheric conditions and cooling

requirements. The ECONSR value will be passed to the econo-

mizer submaster loop, which will modulate dampers to main-

tain SAT at ECONSR level. The Economizer inputs and out-

puts are shown in Tables 9 and 10.

Table 9 — Economizer Inputs

INPUTS TYPE

Unit Type User Conﬁgured

Fan State Internal Parameter

Current Mode Internal Parameter

Space Temperature (SPT) Analog Input

Supply-Air Temperature

(SAT)

Analog Input

Return-Air Temperature

(RAT)

Analog Input

Outdoor-Air Temperature

(OAT)

Analog Input

Enthalpy Discrete Input

Stages of DX Cooling Internal parameter

Occupied Cooling Set Point

(OCSP)

User Conﬁgured, default = 78° F

Occupied Heating Set Point

(OHSP)

User Conﬁgured, default = 68° F

Supply-Air Set Point (SASP) User Conﬁgured, default = 55° F

High OAT Economizer

Lockout (OATL)

User Conﬁgured, default = 65° F

Space Temp. Reset Internal Parameter

External SAT Reset Internal Parameter

Table 10 — Economizer Outputs

OUTPUTS TYPE

ECONSR Economizer Submaster Reference

SEQUENCE OF OPERATION

1. The control will check the following qualifying condi-

tions if atmospheric cooling is possible:

THERMOSTAT UNITS:

• thermostat is calling for Cool, indoor fan is ON

• enthalpy is low

• SAT reading is available (or Compressors are ON)

• OAT reading is available

•OAT≤OATL

• economizer position is NOT forced

SENSOR CONTROLLED UNITS:

• indoor fan has been ON for at least 30 seconds

• enthalpy is low

• OAT reading is available

• CV units: SPT reading is available

• VAV units: SPT or RAT reading is available

• VAV Units: SAT reading is available (or compressors

are ON)

•OAT≤TEMP, where TEMP is SPT (CV), RAT, or SPT

(VAV)

• VAV units with OHEN (Occupied Heating Enable) en-

abled, and TEMP ≥ OHSP + 1.0, where TEMP is RAT,

or SPT if RAT reading is not available

• Economizer position is NOT forced

• unit is not in heat mode

If any of the above conditions are not met, the ECONSR

will be set to its MAX limit. The next 2 steps will be

skipped.

2. If stages of DX cooling are greater than 0, ECONSR is

set to its minimum limit and the next step is skipped.

3. Calculate submaster reference ECONSR as follows:

THERMOSTAT UNITS:

ECONSR = PID function on (SASP − SAT)

CONSTANT VOLUME UNITS WITH SENSORS:

ECONSR = PID function on (set point − SPT), where:

set point = (OCSP+OHSP/2, when OATL<OAT<68

set point = OCSP − 1, when OAT ≤ OATL

set point = OHSP + 1, when OAT ≥ 68

VARIABLE AIR VOLUME UNITS:

ECONSR = PID function on (SASP + RESET − SAT)

where RESET is the greater of Space Temperature

Reset Value or External SAT Reset.

ECONOMIZER CONTROL SUBMASTER LOOP (CCN/

Remote Start/Stop Only) — The Economizer Control Sub-

master inputs and outputs are shown in Tables 11 and 12.

Table 11 — Economizer Control

Submaster Loop Inputs

INPUTS TYPE

Fan State Internal Parameter

Economizer Submaster ref.

(ECONSR)

Internal Parameter

Supply-Air Temperature (SAT) Analog Input

Outdoor-Air Temperature (OAT) Analog Input

IQMP (minimum position) Internal Parameter

Current Mode Internal Parameter

ESG (Submaster Gain Limit) User Conﬁgured, default = -7.5

TEMPBAND

(OAT Temperature Band)

User Conﬁgured, default = 25

ECOBAND

(Damper Movement Band)

User Conﬁgured, default = 0

CTRVAL

(Damper Center Value)

User conﬁgured, default = 70

Table 12 — Economizer Control

Submaster Loop Outputs

OUTPUTS TYPE

ECONPOS Economizer Damper Position %

Sequence of Operation

1. If a compressor is on and the economizer is usable, the

dampers will be open 100% and the rest of the sequence

of operation is omitted.

2. If the indoor fan is off (or has been on for less than

30 seconds), the supply-air temperature reading is not avail-

able, or the HEAT mode is active, the economizer posi-

tion (ECONPOS) will be at the minimum position (IQMP).

The rest of the sequence of operation is omitted.

3. If the OAT reading is available and the OAT <45 F, the

rate of damper movement will be limited to 1% every

4 seconds. Rate limiting will be stopped (allowing damp-

ers to go to the commanded position 1% every 0.9 sec-

onds) when the OAT ≥ 46 F.

4. This loop will adjust its Submaster Gain with changes in

outdoor-air temperature.

1 2 ... 6 7 8 9 10 11 12 13 14 15 16 ... 43 44

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