Brochure

PowerPact H-, J-, and L-Frame Circuit Breakers

Installation Recommendations

152

Altitude Derating

Altitude does not significantly affect the characteristics of PowerPact H-, J-, and L-frame circuit

breakers circuit breakers up to 6560 ft. (2000 m). Above this altitude, it is necessary to take into

account the decrease in the dielectric strength and cooling capacity of air.

The following table gives the corrections to be applied for altitudes above 6560 ft. (2000 m). The

breaking capacities remain unchanged.

Frequency Derating

Application of H- and J-frame circuit breakers at frequencies above 60 Hz requires that special

consideration be given to the effects of high frequency on the circuit breaker characteristics. Thermal

and instantaneous operations must be treated separately.

At frequencies below 60 Hz, the thermal derating of PowerPact H and J-frame circuit breakers is

negligible. However, at frequencies above 60 Hz, thermal derating is required.

One of the most common high frequency applications is at 400 Hz. For 400 Hz derating information,

see Page 27.

For more information, refer to Data Bulletin 0100DB0101, Determining Current Carrying Capacity in

Special Applications.

2000 M

Table 139: Altitude Derating

Altitude

6560 ft

(2000 m)

9840 ft

(3000 m)

13120 ft

(4000 m)

16400 ft

(5000 m)

Dielectric withstand voltage 3000 V 2500 V 2100 V 1800 V

Insulation voltage V

800 V 700 V 600 V 500 V

Maximum operational voltage V

690 V 590 V 520 V 460 V

Average current capacity (A) at 104°F (40°C) I

x 1 0. 0.96 0.93 0.9