PROCESSOR MODULE (PSIO) Ð The PSIO is the brain of the PIC (Fig. 11). This module contains all the operating software needed to control the chiller. The 19XL uses 3 pres- sure transducers and 8 thermistors to sense pressures and tem- peratures. These are connected to the PSIO module. The PSIO also provides outputs to the guide vane actuator, oil pump, oil heater, hot gas bypass (optional), motor cooling solenoid, and alarm contact. The PSIO communicates with the LID, the SMM, and the optional 8-input modules for user inter- face and starter management.

STARTER MANAGEMENT MODULE (SMM) Ð This mod- ule is located within the starter cabinet. This module ini- tiates PSIO commands for starter functions such as start/ stop of the compressor, start/stop of the condenser and chilled water pumps, start/stop of the tower fan, spare alarm con- tacts, and the shunt trip. The SMM monitors starter inputs such as ¯ow switches, line voltage, remote start contact, spare safety, condenser high pressure, oil pump interlock, motor current signal, starter 1M and run contacts, and kW trans- ducer input (optional). The SMM contains logic capable of safely shutting down the machine if communications with the PSIO are lost.

LOCAL INTERFACE DEVICE (LID) Ð The LID is mounted to the control center and allows the operator to interface with the PSIO or other CCN devices (Fig. 11). It is the input cen- ter for all local chiller set points, schedules, set-up func- tions, and options. The LID has a STOP button, an alarm light, 4 buttons for logic inputs, and a display. The function of the 4 buttons or ``softkeys'' are menu driven and are shown on the display directly above the key.

6-PACK RELAY BOARD Ð This device is a cluster of 6 pilot relays located in the control center (Fig. 11). It is energized by the PSIO for the oil pump, oil heater, alarm, optional hot gas bypass relay, and motor cooling solenoid.

8-INPUT MODULES Ð One optional module is factory in- stalled in the control center panel when ordered (Fig. 11). There can be up to 2 of these modules per chiller with 8 spare inputs each. They are used whenever chilled water reset, demand reset, or reading a spare sensor is required. The sensors or 4 to 20 mA signals are ®eld-installed.

The spare temperature sensors must have the same temperature/resistance curve as the other temperature sen- sors on this unit. These sensors are 5,000 ohm at 75 F (25 C).

OIL HEATER CONTACTOR (1C) Ð This contactor is lo- cated in the power panel (Fig. 12) and operates the heater at either 115 or 230 v. It is controlled by the PIC to maintain oil temperature during chiller shutdown.

OIL PUMP CONTACTOR (2C) Ð This contactor is located in the power panel (Fig. 12). It operates all 200 to 575-v oil pumps. The PIC energizes the contactor to turn on the oil pump as necessary.

HOT GAS BYPASS CONTACTOR RELAY (3C) (Op- tional) Ð This relay, located in the power panel, (Item 5, Fig. 12) controls the opening of the hot gas bypass valve. The PIC energizes the relay during low load, high lift conditions.

CONTROL TRANSFORMERS (T1-T4) Ð These trans- formers convert incoming control voltage to either 21 vac power for the PSIO module and options modules, or 24 vac power for 3 power panel contactor relays, 3 control solenoid valves, and the guide vane actuator. They are located in the power panel. See Fig. 12.

CONTROL AND OIL HEATER VOLTAGE SELECTOR (S1)

ÐIt is possible to use either 115 v or 230 v incoming con- trol power in the power panel. The switch is set to the volt- age used at the jobsite.

 

LEGEND

 

 

1

Ð T2 Ð 24 vac Power Transformer for Hot Gas Bypass Relay,

4

Ð T1 Ð 24 vac, Control Center Transformer

 

Oil Pump Relay, Oil Heater Relay, Motor Cooling Solenoid,

5

Ð 3C Hot Gas Bypass Relay Location

 

Oil Reclaim Solenoid

6

Ð Oil Pump Terminal Block

2

Ð Oil Pressure Switch

7

Ð Factory Terminal Connections

3

Ð T4 Ð 24 vac, Optional 8-Input Module Transformer

8

Ð T3 Ð 24 vac Guide Vane Actuator Transformer

Fig. 12 Ð Power Panel with Options

13

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Carrier 19XL specifications Control and OIL Heater Voltage Selector S1, Power Panel with Options
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19XL specifications

The Carrier 19XL is a highly regarded commercial heating and cooling solution, designed to provide optimum performance and energy efficiency in various applications. This rooftop unit is engineered to meet the diverse needs of businesses, making it an ideal choice for those requiring reliable climate control in their facilities.

One of the standout features of the Carrier 19XL is its advanced cooling and heating capabilities. The unit utilizes a high-efficiency scroll compressor that ensures a quieter operation and improved reliability. The system can operate across a wide range of temperatures, making it versatile for various climates. Additionally, it offers both cooling and heating options, allowing for year-round comfort.

Energy efficiency is a focal point of the 19XL design. With an impressive Seasonal Energy Efficiency Ratio (SEER) and Heating Seasonal Performance Factor (HSPF), this unit not only helps reduce energy costs but also supports environmental sustainability initiatives. The unit is equipped with environmentally friendly refrigerants, further contributing to lower greenhouse gas emissions.

The Carrier 19XL features a user-friendly control system, allowing for easy monitoring and management of the unit's performance. This control system is designed to maximize energy savings, offering features such as demand control ventilation and integrated economizers that facilitate the use of outdoor air for cooling, reducing reliance on mechanical systems when conditions allow.

Construction-wise, the Carrier 19XL is built to withstand tough environmental conditions. Its robust cabinet is made from galvanized steel, providing durability and protection against the elements. The design also includes insulation to minimize noise levels, creating a more comfortable indoor environment.

Maintenance is a key consideration in the design of the 19XL. The unit features accessible service ports and a simplified access panel, allowing technicians to perform routine maintenance with ease. This proactive design helps ensure the longevity of the system and minimizes downtime, keeping operations running smoothly.

In summary, the Carrier 19XL is an exceptional choice for commercial heating and cooling needs. With its energy-efficient features, advanced technology, and durable construction, it stands out as a reliable solution for businesses looking for sustainable climate control options.
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