ELBOW 3H0120 - Caterpillar

Illustration 1 g03886291Load Add and Load Shed
Load add and load shed are complementary features that work together to add and shed loads while the EMCP 4.4 SCP is running. For further information refer to Application and Installation Guide, LEBE0040, "EMCP 4.4 Supervisory Control". The following sections outline these two features.Supervisory Load Add
Overview
The load add feature on the EMCP 4.4 SCP will automatically add loads in a priority-based manner. This feature occurs when the generating capacity of the system is sufficient to power all connected loads.The load add feature consists of an initial conditional load add period followed by a load sensitive load add period. The load add feature enters the load sensitive load add period when the conditional load add timer expires.The supervisory control panel can be configured to add or remove all loads when the EMCP 4.4 SCP does not have a run signal.Conditional load add
The conditional load add timer starts when a unit detects bus voltage. The conditional load add timer is still used even if the load sense load demand (LSLD) is disabled on the generator system sets based on the last setting of the timer.The EMCP 4.4 SCP does not need to wait for all available generator sets to have synchronized onto the bus before the unit starts to add loads.Load steps are added based on priority. The highest priority will have the lowest number. Priorities are assigned using "Load Add Priority for Load Step N (setpoint)".If multiple load add steps are programmed to the same priority, the lower number load step has priority over the higher number load step. Although not required, the recommended action is to program each step for the matching priority.Adding a load step
A load step is added if the following are true:
Capacity headroom is greater than the load step rating of the load step (both kW and kVAR)
The "Load Add Minimum Generator Load Step Time Delay (setpoint)" (triggered for the previous load step added) has expired.
The "Load Shed Latch Enable for Load Step N (setpoint)" is not enabled for that load step
The "Load Add Priority for Load Step N (setpoint)" number is less than or equal to the "Load Add Generator Supplies Maximum Load Step Priority" numberLoad step time delay
The "Load Add Minimum Generator Load Step Time Delay" starts to time when any load step is added. Minimum delay is still enforced between successive non-zero load add steps when the capacity is such that two or more load steps may be applied. If the load step is defined as rated 0 kW and 0 kVAR, then this time is not applied and the load step may be added immediately after the previous.Note: A "Load Add Minimum Utility Load Step Time Delay" (setpoint) should be used for load steps above the "Load Add Generator Supplied Maximum Load Step Priority" (setpoint) number.Once the "Load Add Minimum Generator Load Step Time Delay" starts to time, a timer starts against the "Load Add Duration for Load Step N" (setpoint) time. This timer tracks the