Abstract: In order to ensure a long-term reliable operation of the DCS cabinet’s 220 V AC power cable, it was needed to confirm whether the conductor temperature rise of power cable meet the requirement of the cable specification. Based on the actual data in site and the theory of numerical heat transfer, conservative model was established, and the conductor temperature was calculated. The calculation results show that the cable arrangement on the cable tray will not lead to the conductor temperature rise of power cable over than the required temperature in technical specification.