Johnson Controls A350A/B Data Sheet

FANs 930, 930.5, 125, 121 Product/Technical Bulletin A350 Issue Date 0614

System 350™

A350A/B Electronic Temperature Control

The A350A/B Series is an on/off electronic temperature control with a Single-Pole, Double-Throw (SPDT) relay output and a Light-Emitting Diode (LED) relay status indicator. Designed to operate with both heating and cooling equipment, this control includes an adjustable differential and an interchangeable temperature sensor.

As are all System 350™ products, the A350A/B is housed in a NEMA 1, high-impact plastic enclosure. The modular design provides easy, plug-together connections for quick installation and future expandability.

Figure 1: A350 Series Electronic

Temperature Control

Features and Benefits

 Modular Design Enables stage, display, and power modules to

be purchased and installed as needed

 Plug-together Connectors

and 35 mm DIN Rail Mounting

 Two Standard Models

Cover Wide Setpoint Ranges

-30 to 130°F (-34 to 55°C) or 90 to 250°F (32 to 121°C)

 Wide Adjustable Differential

of 1 to 30F° (0.6 to 16.7C°)

 Field-Selectable Mode

Jumpers

 Available with Either

External or Concealed Setpoint

Eliminates wiring between modules and reduces installation costs

Reduces inventory by encompassing temperature ranges required to support the majority of Heating, Ventilation, Air Conditioning, and Refrigeration (HVAC/R) applications

Enables the user to match equipment cycle rate and/or sequencing for a given application

Operates in both heating and cooling applications

Helps deter accidental and unauthorized adjustments

 Interchangeable

Temperature Sensors

Increases versatility and serviceability

pplication

The A350A/B Temperature Control can be used as a standalone device or in conjunction with other System 350 plug-together modules to control single or multiple-stage HVAC or refrigeration equipment. Typical applications include:

 frozen/refrigerated food cases  cooling tower control  beverage/milk coolers  chiller staging  space temperature control

A typical System 350 Temperature Control arrangement includes the following:

 A350A/B Temperature Control  S350 Stage Modules  D350 Digital Temperature Sensor/Setpoint Display

Module

 Y350R Power Module (or Class 2

24 VAC transformer)

 A99B Series Temperature Sensor

IMPORTANT: Use this A350A/B Electronic

Temperature Control only as an operating control. Where failure or malfunction of the A350A/B control could lead to personal injury or property damage to the controlled equipment or other property, additional precautions must be designed into the control system. Incorporate and maintain other devices, such as supervisory or alarm systems or safety or limit controls, intended to warn of or protect against failure or malfunction of the A350A/B control.

IMPORTANT: Utiliser ce A350A/B Electronic

Temperature Control uniquement en tant que dispositif de régulation. Lorsqu'une défaillance ou un dysfonctionnement du A350A/B control risque de provoquer des blessures ou d'endommager l'équipement contrôlé ou un autre équipement, la conception du système de contrôle doit intégrer des dispositifs de protection supplémentaires. Veiller dans ce cas à intégrer de façon permanente d'autres dispositifs, tels que des systèmes de supervision ou d'alarme, ou des dispositifs de sécurité ou de limitation, ayant une fonction d'avertissement ou de protection en cas de défaillance ou de dysfonctionnement du A350A/B control.

2 System 350 A350A/B Electronic Temperature Control Product/Technical Bulletin

peration

The A350A/B Temperature Control operates on 24 VAC and provides an SPDT relay output. A front panel LED lights to indicate when the relay is energized. Adjustable features include:

Setpoint Adjustment

Setpoint is defined as the temperature at which the A350A/B’s relay de-energizes. Use the Setpoint Dial on the front of the A350A/B to adjust setpoint. See Figure 2.

 setpoint  differential  heating/cooling mode

IMPORTANT: All System 350 Controls are

designed for use only as operating controls. Where an operating control failure would result in personal injury and/or loss of property, it is the responsibility of the installer to add devices (safety, limit controls) that protect against, or systems (alarm, supervisory systems) that warn of, control failure.

Differential Adjustment

Differential is defined as the change in sensor temperature between energization and deenergization of the relay. Adjustment of the A350A/B differential is made using the potentiometer marked DIFF. See Figure 2 for its location. Refer to Table 5 for adjustment ranges.

24V COM VDC

SEN

DIFF

(Differential

Potentiometer)

Relay

LED Indicator

Figure 2: A350A/B Board Layout and

Setpoint

Dial

Module

Connector

Jumper Bl ock

Relay

Terminal Locations

Position

Heating

Cooling

Heating/Cooling Mode Adjustment

With Heating mode selected, the differential is below setpoint. The relay and LED indicator will de-energize as the temperature rises to the setpoint. As the temperature drops to the setpoint minus the differential setting, the relay will energize and the LED illuminates. Refer to Figure 6.

With Cooling mode selected, the differential is above setpoint. The relay and LED indicator will de-energize as the temperature drops to setpoint. As the temperature rises to the setpoint plus differential setting, the relay will energize and the LED illuminates.

As shipped from the factory, the heating/cooling jumper blocks are installed in the horizontal (cooling) position. See Figure 2.

System 350 A350A/B Electronic Temperature Control Product/Technical Bulletin 3

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