Sequence fault — Chiller → cooling tower.

Trigger, action plan, and escalation criteria.

Related metric

chiller_plant_operational_compliance

Trigger

system_on=1 AND any_tower_on=0 sustained ≥ seq_fail_duration (raises SEQ-FAIL Chiller→Tower)

Value drivers

Asset lifespan Energy savings Avoided truck rolls

Preconditions

Chiller ON/OFF and cooling-tower run status mapped as Modbus binary points and rolled up into system_on and any_tower_on. Interlock #03 confirmed to apply to the plant, and whether it is evaluated per individual chiller or as a tower group agreed, before the alarm is armed. seq_fail_duration is a configurable server-side attribute; the chiller ON/OFF Modbus mapping is confirmed per plant.

Human role

Primary — Keedian reads the interlock and raises the alarm; the BMS sequence-logic correction is the plant-service vendor's. Operators confirm the fault, notify the customer, and coordinate the vendor referral.

Action plan

(1) Point-mapping sanity check first — confirm chiller-ON and tower-run points are current and correctly mapped before treating the fault as real. (2) Confirm the condition is sustained past seq_fail_duration, not a tower-staging transient. (3) Once confirmed, notify the customer and the plant-service vendor out of cycle — with no heat rejection the chiller drifts toward high condensing temperature and a protective shutdown. (4) Attribute the fault to the chiller and the tower(s) evaluated; Keedian surfaces the finding, the vendor changes the sequence logic on the BMS side.

Escalation

(1) Chiller confirmed running with no tower proven → out-of-cycle customer + plant-vendor alert before efficiency loss becomes a protective shutdown. (2) Recurrence on the same plant after correction → flag a controls or sensor fault for a deeper vendor engagement. (3) Open question — whether the fault evaluates towers as a group or per individual chiller — unresolved for the plant → confirm the evaluation basis with the vendor before arming, so a staged-off standby tower is not scored as a fault.

Prevention

(1) Verify chiller-ON and tower-run points at onboarding and confirm interlock #03 and its evaluation basis (group vs per-chiller) before arming. (2) Calibrate seq_fail_duration to ride through tower staging but catch a genuine loss of heat rejection. (3) Log recurring faults per plant to surface a developing controls or sensor issue for the vendor.