Carrier 30GK Demand limit by 0-10 V d.c. signal, Capacity control, Circuit loading sequence

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5.8 - Demand limit

Generally, demand limit is used by an energy management system in order to restrict the unit electricity consumption.

The PRO-DIALOG Plus control system for 30GX & 30HX provides two methods of demand limit:

•By reference to a limiting signal from a user-controlled volt-free contact: the capacity of the unit cannot exceed the demand limit setpoint (which can be modified in the Setpoints menu) when the limit contact is closed.

•By reference to an external 0-10 V d.c. signal: the capacity of the unit cannot exceed the demand limit imposed by this external signal. It is a linear function and its para-meters are configurable in the User1 menu (voltages at 0% limitation and 100% of limitation). This function is not available if Reset by reference to an external 0-10 V d.c. signal has already been selected.

Whatever the method used, demand limit is active in all operating types: Local, Remote or CCN. However, in Local operating type, demand limit can be disabled with keypad commands (see section 4.3.3) and in CCN operating type, demand limit can be controlled directly with the aid of CCN commands.

NOTE: A limitation value of 100% means that the unit may call upon the full array of its capacity stages.

Here is an example of demand limit by an external 0-10 V d.c. signal. This example assumes that the limitation parameters are such that at 0 volt the authorised capacity shall be maximum capacity, and at 10 volts the authorised capacity shall be zero (this is the default configuration).

Demand limit by 0-10 V d.c. signal

 

 

No demand limit

Maximum permitted

capacity

Total demand limit

 

 

 

0-10 V dc demand limit

5.9 - Capacity control

This function activates the compressors and capacity unloaders to keep the entering or leaving water temperature at its setpoint. The precision with which this is achieved depends on

the capacity of the water loop, the flow rate, the load, and the number of stages available on the unit.

The control system continuously takes account of the tempera- ture error with respect to the setpoint, as well as the rate of change in this error and the difference between entering and leaving water temperatures, in order to determine the optimum moment at which to add or withdraw a capacity stage.

NOTE: If the same compressor undergoes too many starts (per hour) this automatically brings about reduction of compressor starts, which makes leaving water temperature control less precise.

5.10 - Determining the lead circuit

This function commands the start/stop sequence of the two refrigerant circuits called A and B. The circuit authorised to start first is the lead circuit. Three methods can be configured by the user in the Configuration menu:

•Auto mode: the control system determines the lead circuit so as to equalise the number of starts on each circuit (value weighted by the operating times of each circuit). Thus, the circuit with the least number of starts is always given precedence to start. The lead circuit is stopped last. This function is only available in two-circuit units.

NOTE: If one circuit has more unloaders than the other, this circuit is always the lead circuit, independent of the configuration and the operating hours of the two circuits.

•Circuit A as leader: Circuit A is always the lead circuit. It is the first to start and the last to stop.

•Circuit B as leader: Circuit B is always the lead circuit. It is the first to start and the last to stop. This choice is only available in two-circuit units.

5.11 - Circuit loading sequence

Two circuit loading sequences are available. The choice of sequence can be configured by the user in the Configuration menu (see section 4.5.7.3). This function is only available in two-circuit units.

•Balanced circuit loading: If this sequence is selected, the control system tries to keep the capacity of circuits A and B equal as the total load on the unit increases or decreases.

•Loading with priority given to one circuit: If this sequence is selected, the control system loads the lead circuit completely before the second circuit starts up. When there is a demand limit, the second circuit is unloaded first.

NOTE: If the unit is air-cooled and if the saturated condensing temperature of one of the two circuits is lower than 0°C at the start-up of one circuit, the priority capacity loading sequence of the circuits is used by the control, independent of the configuration.

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Contents 30GK Series PRO-DIALOG Control Installation, operation and maintenance instructionsTable of Contents Safety Considerations Diagnostics Troubleshooting Avoiding electrocution Safety ConsiderationsGeneral Abbreviations used General DescriptionGeneral Control board Hardware DescriptionElectronic boards Control boxRed LED Board addressesGreen LED Orange LED CCN/clock boardEvaporator leaving water temperature sensor Evaporator entering water temperature sensorCondenser entering and leaving water temperature sensors Heat reclaim condenser entering/leaving water temperaturesUser connections Description Connector Terminal ChannelAvailable Terminals RemarksLocal interface general features Setting UP PRO-DIALOG Plus ControlMain interface Main Interface Button Name DescriptionUnit start/stop control Stopping the unit in local modeDescription Starting unit and selecting an operating typeMenus Modifying the value of a parameter/access to a sub- menuSelecting a menu Selecting a menu itemStructure MenuStatus Menu treeInformation Menu Format Units Description Description of the Information menuTemperatures Menu Format Units Comments Description of the Temperatures menuDescription of the Pressures menu Pressures Menu Format Units CommentsSetpoints Menu Format Units Range Comments Description of the Setpoints menuDescription of the Outputs/Tests menu General Description of the Inputs menuMenu description Inputs Menu Format Units CommentsFormat Units Description Manual tests Description of the Configuration menu GeneralPassword SUB-MENU Holiday Configuration SUB-MENU Period ConfigurationUser 1 Configuration SUB-MENU Format Units Default Comments Description of the User 1 Configuration sub-menuDate & Time Configuration SUB-MENU Format Comments Description of the User 2 Configuration sub-menuDescription of Date and Time configuration sub Menu Description of the Holidays sub-menus Typical timer programDescription of the Broadcast sub-menu Item # Format CommentsDescription of the Alarms History menu Description of the Alarms menuBroadcast Configuration SUB-MENU Item # Format Comments Alarms Menu Item # Format DescriptionDescription of the Runtimes 1 menu Maintenance menu descriptionRuntime menu description Description of the Runtimes 2 menu PRO-DIALOG Plus Control Operation Chilss Contact Type Mode ShutdownStart/stop control Heating/cooling selectionCondenser water pump control Evaporator water pump control Control interlock contactEvaporator heater control Control pointDemand limit Demand limit by 0-10 V d.c. signalCapacity control Determining the lead circuitControlling the EXV Slave compressor start-up sequenceHead pressure control on air-cooled units Head pressure control on water-cooled unitsHigh pressure load shedding function Master/slave assemblyPumping down Controlling Pro-Dialog Plus units with a System ManagerDisplaying alarms Diagnostics TroubleshootingResetting alarms Optional heat reclaim moduleAlarm Code Descriptions Alarm codesCCN DGT only for units with low-temperature option Compressor faults 6.4.1.1 GeneralCompressor protection devices Starter Guard

30GK specifications

The Carrier 30GK is a prominent chiller model known for its efficiency and reliability in various commercial and industrial applications. Offering a blend of advanced technology and robust design, the 30GK series caters to diverse cooling needs while maintaining energy efficiency and low operational costs.

One of the standout features of the 30GK is its use of the latest scroll compressor technology. This contributes to its efficient performance, enabling the chiller to operate at optimal levels while minimizing energy consumption. The scroll compressor is known for its quiet operation, which reduces noise pollution, making it an ideal choice for buildings located in noise-sensitive environments.

The 30GK chiller series is equipped with microchannel coil technology, which allows for improved heat exchange efficiency. The microchannel design uses a compact coil structure that enhances refrigerant flow and reduces refrigerant volume, leading to a smaller footprint compared to traditional coil designs. This innovative design not only saves space but also improves the chiller's overall performance.

Another notable characteristic of the Carrier 30GK is its environmental consciousness. The chiller operates using environmentally friendly refrigerants, aligning with modern regulations and sustainability goals. Its design incorporates energy-efficient components that contribute to significant reductions in greenhouse gas emissions, making it suitable for environmentally responsible projects.

Moreover, the 30GK is designed for easy serviceability, with accessible components that simplify maintenance. This feature is particularly important for facility managers seeking to minimize downtime and keep maintenance costs low. The chiller also includes advanced monitoring and control systems, which enable real-time performance tracking and diagnostics, enhancing operational efficiency.

In terms of performance, the 30GK chiller is known for its wide capacity range, making it versatile for various applications. Whether for commercial spaces, industrial processes, or large buildings, the 30GK can meet the cooling demands reliably.

Overall, the Carrier 30GK chiller represents a perfect balance of cutting-edge technology, energy efficiency, and sustainability. Its features make it a leading choice in the market, suited for those looking to invest in high-quality and dependable cooling solutions.
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