01Record a complete set of site data
Under reasonably stable conditions, record inlet and outlet temperature, flow, operating pressure, three-phase voltage and current, output of each heater bank, ambient temperature and insulation condition. Note the time from startup to target temperature and the process load during the measurement.
If flow or inlet temperature keeps changing, warm-up time cannot be compared directly with the design value. Confirm sensor locations and instrument condition before comparing operating cases.
02Check electrical input and heater banks
Actual element output depends on terminal voltage and connection. Check supply voltage, phase balance, wiring diagram, protective devices and current in each bank. A bank that is not energized, a poor connection or a voltage deviation can reduce total output.
Measurements and repairs should be performed by qualified electrical personnel under site safety procedures. Do not open an enclosure while energized if it is not designed for live maintenance.
03Compare flow, fluid and heat loss
If actual flow exceeds the design value, each unit of fluid may receive a smaller temperature rise; very low flow may trigger power limitation or protection. Fluid heat capacity, density, viscosity or phase that differs from the calculation basis also changes duty.
Inspect pipe insulation, thermal bridges at valves and flanges, bypass flow and ongoing downstream heat demand. Required power includes startup duty and heat continuously removed during operation; the nameplate rating alone does not describe every case.
04Review control and temperature measurement
Confirm controller setpoint, output percentage, bank sequencing, sensor type and mounting location. A probe near a local heat source, in a poorly mixed area or with calibration drift may not represent the true fluid condition.
After comparing data, decide whether to adjust control, repair equipment, improve insulation or recalculate duty. Changes to pressure boundaries, materials or protective settings should be reviewed by the responsible design and equipment parties.