Two zones with the same percentage command may deliver different power because of element resistance, supply voltage, phase loading, controller type, wiring loss, or replacement-component mismatch. The sheet responds to delivered energy, not the displayed percentage.
Voltage, current, and calculated power should be compared by zone under a stable command. Three-phase systems should also be checked for phase current and voltage imbalance. The thermal map should then be related to the electrical results; a power imbalance that does not align with the sheet pattern may indicate reflectors, spacing, or airflow.
Electrical loading should be corrected at the source. Zone percentages may be tuned for intentional process heating, but they should not compensate for an unintended supply or hardware imbalance. Component ratings and conductor temperature must remain within design limits.