Small data center customer in Boise on Idaho Power Schedule 19 large general service. They have six precision air conditioning units that are supposed to stage based on cooling load but something's wrong with the sequencing. Multiple units start simultaneously during high load periods causing demand spikes up to 180kW above baseline. Normal cooling load is around 120kW. Anyone familiar with Liebert iCOM controls and staging logic? The local service tech seems stumped.
Idaho Power Schedule 19 - data center HVAC sequencing question
Avista territory here but dealt with Liebert units before. The iCOM system has a lead-lag rotation feature that should prevent simultaneous starts. Check if the communication bus between units is working properly - if units can't talk to each other they'll all try to satisfy cooling load independently. Also verify the staging timers are programmed correctly, should be 3-5 minute delays between starts.
Georgia Power Schedule PL-1 customer here with similar precision cooling setup. Warren, the issue might be temperature sensor placement. If sensors are in different microclimates within the data center, they can all read high temps simultaneously and trigger multiple unit starts. Make sure sensors are in representative locations and consider adding a master sensor that coordinates the staging sequence.