Operating d II CT4 devices ensures a lower maximum operating temperature, which increases safety. The term “d” denotes flameproof equipment. The explosion-proof rating for CT4 is superior.
Temperature group of electrical equipment | Maximum allowable surface temperature of electrical equipment (℃) | Gas/vapor ignition temperature (℃) | Applicable device temperature levels |
---|---|---|---|
T1 | 450 | >450 | T1~T6 |
T2 | 300 | >300 | T2~T6 |
T3 | 200 | >200 | T3~T6 |
T4 | 135 | >135 | T4~T6 |
T5 | 100 | >100 | T5~T6 |
T6 | 85 | >85 | T6 |
T4-rated explosion-proof equipment holds a higher standard and can substitute for BT4-rated devices; thus, using CT4 instead of BT4 ensures compliance and enhanced safety.