Example 5B Ð 4 to 20 mA and Internally or

Externally Powered Reset

In this example, the unit set point is reset from full load at 4 mA to a maximum reset value of 10 F (5.5 C) at 20 mA. Internally powered 4 to 20 mA option is used in this example.

NOTE: To use externally powered reset, when CRTYP

appears, press so CRTYP 4 appears in the

display. The remainder of the information in the fol- lowing example applies to either type of reset.

KEYPAD

DISPLAY

COMMENTS

ENTRY

RESPONSE

 

 

FLD CFG

 

 

CRTYP 0

Scroll past to reset type

 

CRTYP 1

Internally powered reset

 

selected

 

 

 

RESET

 

 

CRT1 0

Reset at 20 mA is 0

 

CRT1 10

Reset at 20 mA is 10

 

 

 

Example 5C Ð Using Return Fluid

Temperature Reset

KEYPAD

DISPLAY

COMMENTS

ENTRY

RESPONSE

 

 

 

 

 

 

Field con®guration

 

FLD CFG

subfunction of

 

 

service function

 

CSPTYP X

Scroll past single/dual

 

CRTYP 0

Display shows no reset

 

type has been selected

 

 

 

CRTYP 3

Return ¯uid temperature

 

is selected and activated

 

 

 

RESET

Reset set points

 

 

 

Temperature Reset Based on External Temperature Ð If de- sired, temperature reset can be based on an external tem- perature, such as space or outdoor-air temperature. This re- quires a thermistor (T10, Part No. 30GB660002) located in the space or outdoor air and wired to terminals as follows (also see Field Wiring section on page 69 and Fig. 6):

4 in/4 out Module Ð J7-15 and J7-16.

At the ®eld con®guration step, enter set points as de- scribed in Examples 5A-5C on pages 39 and 40. Then

select external temperature reset by entering

when

CRTYP 0 appears. See Fig. 7.

Temperature Reset Based on 4-20 mA SignalÐ If desired, temperature reset can be based on a 4-20 mA signal. For proper connections, refer to Field Wiring section on page 69 and Fig. 8.

At the ®eld con®guration step, select 4-20 mA reset by

entering (internally powered) or (externally pow-

ered) when CRTYP 0 appears. Then enter set points as de- scribed previously in Examples 5A-C. See Fig. 8.

Subfunction displays demand limit set points.

Demand Limit, 2-Stage Switch Control Ð This control has been designed to accept demand limit signals from a build- ing load shedding control. The demand limit function pro- vides for 2 capacity steps. The keypad is used to set the 2 demand limit set points, which range from 100 to 0% of ca- pacity. Capacity steps are controlled by 2 ®eld-supplied re- lay contacts connected to the designated chiller terminals. (See Field Wiring section on page 69 and Fig. 7.)

Fig. 5 Ð Cooling Return Fluid Reset

40

Page 39 Page 41
Page 40
Image 40
Carrier 30GN040-420 Example 5C Ð Using Return Fluid Temperature Reset, Keypad Display Comments Entry Response
Page 39 Page 41

30GN040-420 specifications

The Carrier 30GN040-420 is a well-regarded model within the industry of chillers, designed to deliver efficient cooling solutions for a variety of commercial applications. Its compact design and advanced technology make it an ideal choice for businesses looking to optimize their HVAC systems.

One of the standout features of the Carrier 30GN series is its flexibility. This chiller model is available in a range of capacities, specifically from 40 to 420 tons, allowing for customized solutions based on specific cooling demands. Such versatility enables this unit to cater to a broad array of installations, from small commercial spaces to larger industrial facilities.

The Carrier 30GN040-420 utilizes a scroll compressor design, known for its reliability and efficiency. The scroll technology allows for a reduction in the number of moving parts, resulting in lower maintenance costs and increased durability. Additionally, the unit operates with environmentally friendly refrigerants such as R-410A, promoting sustainability without compromising performance.

Energy efficiency is another significant aspect of this model. The 30GN series is designed to provide high energy efficiency ratios (EER), which translates to lower operational costs for users over the lifespan of the unit. This is particularly beneficial in an era where energy costs are consistently rising.

The advanced controls found within the Carrier 30GN040-420 further enhance its performance and ease of use. The unit is equipped with a microprocessor-based control system that allows for precise temperature management while providing valuable diagnostic information. This feature not only improves the overall reliability of the system but also facilitates proactive maintenance, reducing the risk of unscheduled downtime.

Moreover, the design of the Carrier 30GN040-420 emphasizes quiet operation, making it suitable for environments where noise levels must be minimized. This characteristic is critical for applications in hospitals, schools, or office buildings, where a peaceful atmosphere is essential.

In summary, the Carrier 30GN040-420 chiller provides a robust solution for businesses requiring dependable and efficient cooling. Its features, including flexible capacity options, reliable scroll compressors, energy-efficient performance, advanced controls, and quiet operation, position it as a top choice for various commercial and industrial applications. As technology continues to evolve, models such as the 30GN series remain at the forefront, meeting the demands of modern HVAC needs while ensuring sustainability and efficiency.
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