Generator Load Control Object - Metasys - LIT-12011942 - Software Application - ODS Server - 10.1

Metasys Open Data Server Help

Brand
Metasys
Product name
ODS Server
Document type
User Guide
Document number
LIT-12011942
Version
10.1
Revision date
2019-10-14
Language
English

Menu Selection: Insert > Object > Generator Load Control

This object is similar to the Electric Demand Control Object but specifically controls the loads on a backup generator. A given generator can supply a fixed maximum amount of power. A reference to the current load on the generator and the value of the maximum generator output are configured in the object. The Present Value is a value that indicates the level of shed activity needed so the demand does not exceed the maximum power output of the generator. External logic must be used to interpret this value and switch on/off loads.

Note: In the Notes column, letters indicate the following: A - Archive, B - BACnet Array, C - Configurable, D - Default Attribute, F - PM Refresh, O - BACnet Optional, Q - BACnet Required, R - Associate with Reliability, W - Writable.

Table 1. Generator Load Control Object Attributes
Attribute Notes Initial Value Values\Options\Range Description
Present Value W,D,R,F,Q 1 (from Standard object) For the Generator Load Control and Electric Demand Control objects, the Present Value attribute ranges from 1 to 16. Level 1 represents all level release; 16 is the highest level and 2 is the lowest level. When the Present Value increases from 2 to 16, turn ON control to selected facilities. When the Present Value decreases from 16 to 2, turn OFF control to selected facilities. This value presets to 1 when monitoring starts.
Control Type W,C,A Time Ctrl Control_ Type_ Enum_Set (New Define) This attribute provides the means for determining the Present Value. Time Control refers to the value of the Adjust Value of Load property, and determines the Present Value. Value Control refers to the values of Adjust Value of Load property, and determines the Present Value.
Adjust Value of Load Q 0 Units = kW This attribute expresses the value of electric power that can be supplied by a generator minus the current electric power consumed by a generator in kW units.
Priority for Writing W,C,A,Q 11

Low Limit = 3

High Limit = 16

This attribute defines the priority when instructed to start or stop by demand control based on this object. It is a 1 to 16 unsigned integer, with 1 being the highest priority, and 16 being the minimum priority.
Target Value to Supply W,C,A,Q 0 Units = kW This attribute shows the electric power that can be supplied by a generator.
JCI Control Start Reference C,A NULL   This attribute refers to the power voltage of a generator. The Present Value of BI or BV is configured as an object or a property to be set. If the object referred to is not reliable, or the reference of the input object is offline, the Generator Load Control object is unreliable.
JCI Current Consumed WH Reference C,A NULL   This attribute refers to the power consumption of a generator. The Present Value of AI or AV is configured as an object and a property to be set. If the object is not reliable, or the reference of the input object is offline, the Generator Load Control object is unreliable.
Sampling Interval W,C,A 5 Units = seconds This attribute refers to the interval of time in seconds needed to determine the Present Value.

The values of Sampling Interval and Consecutive Samples should be configured in consideration of the update time (polling period) of the object that is set as the reference input. If the object reaches the value that is set in Consecutive Samples, the Present Value is obtained.

Transition Interval W,C,A,O 60 Units = seconds This attribute is the interval of time in seconds needed to determine when the Present Value can be increased by one level in Value Control. The values of Transition Interval are configured in consideration of the update time (ramping period - how fast the Present Value can be ramped up from one level to another) of the load controlled by the object. This interval only applies to values that are positively increasing. If the Present Value of the object is decreasing, this interval does not apply.

When the Present Value is changed to a positive direction such as from 1 to 4, the Present Value should ramp up one level at a time to prevent generator failure because of overload. This property defines an interval to decide when the next increase occurs. For example, if Generator Load Control (GLC) changes the Present Value from 1 to 2, then once the Time Transition Interval expires, GLC changes the Present Value to 3, and so on, until it reaches the desired level. While in transition, the desired level can change and the ramping can be adjusted to the new level.

Consecutive Samples W,C,A 6   See the Sampling Interval attribute for details.
Recovery Power Offset W,C,A 0 Units = kW This attribute represents the offset that counts toward the determining conditions for performing applying control (decrement of level).
Level Value   ALL 0  

This attribute represents the level of available electric power of a generator, measured in a 60 minute period. It defines the load capacity to be decreased when a device at a specified level is turned off.

Although the Level Value attribute is an array of 16 values, only the values 1, 2, 3, 9, 15, and 16 are configurable.

Level Value: Control Status of Register Points Device

1: All levels recovered (all demand controlled devices are OFF).

2: Level 2 devices are turned ON. All other devices are OFF.

3: Level 2 and 3 devices are turned ON. All other devices are OFF.

<4-8>:n/a

9: Devices at level 1 to 9 are turned OFF. All other devices are OFF.

<10-14>:n/a

15: Devices at level 1 to 15 are turned ON. All other devices are OFF.

16: All levels are recovered (all demand controlled devices are ON).