NDM2L—250

1. Applicable Scope and Purpose of Circuit Breaker

The NDM2L-250 molded case circuit breaker with the residual current protection (hereinafter referred to as circuit breaker) applies to infrequent switching of circuits with the AC 50/60Hz, the working voltage of AC415V and the working current up to 250A. With the overload, short circuit and undervoltage protection functions, the circuit breaker can protect lines and power equipment from damage. Meanwhile, they can deal with the personal safety, fire hazards and other potential risks caused due to long-term ground faults that can’t be detected with the overcurrent protection function.

2. Specification and Model Description of Circuit Breaker

3. Main Technical Parameters of Circuit Breaker

Table 2 Main Technical Parameters of Circuit Breaker

a)Selection of the circuit breaker connecting bus or cable cross-section area:
Table 3 Selection of the NDM2L-250 Connecting Bus or Cable Cross-section Area

b)Tightening Torque of the Circuit Breaker Terminal and Mounting Screw
Table 4 Tightening Torque of the Circuit Breaker Terminal and Mounting Screw

c)Derating factor of temperature change for the circuit breaker
Table 5 Derating Factor Table of Temperature Change for the Circuit Breaker

Note: 1) When the operating ambient temperature is below ﹢40℃, the product can be used normally without derating capacity.
2) The above derating factors are measured at the frame current.

d)High-altitude derating factor of the circuit breaker

Table 6 High-altitude Derating Factor Table of Circuit Breaker

4.Normal Working Environment of Circuit Breaker
1)The altitude of the installation site doesn’t exceed 2,500m. See the “High-altitude Derating Factor Table of Circuit Breaker” for the derating factor at the altitude;
2)The ambient temperature is -35℃ ~ + 70℃; the average within 24 h shall not be more
than +35℃. If the ambient temperature is higher than +40℃, the user needs to reduce the capacity. See the “Derating Factor Table of Temperature Change for the Circuit Breaker” for the derating factor;
3)Its relative humidity at an ambient temperature of +40℃ should not exceed 50%. A higher
relative humidity is allowed at a lower temperature. For example, the relative humidity at 20℃ can reach 90%; for frost due to temperature change, the corresponding measures should be taken;
4)The product can withstand the effects of wet air, salt mist, oil mist and mould;
5)The installation category of the circuit breaker connected to the main loop is: Category Ⅲ (power distribution and control level), The installation category of the circuit breaker not connected to the main loop is: Category Ⅱ (load level);
6)The pollution level is Level 3;
7)The product should be installed in places that are free from explosive media, media corrosive to metal, insulation damaging gas, and conductive dust, which should be also avoided from snow and rain;
8)In case of stricter user conditions than the above description, negotiate with the manufacturer.

5.Outline and Mounting Hole Dimensions of Circuit Breaker
a)Outline and mounting hole dimensions of circuit breaker

Note: The limit deviation not indicated with the tolerance dimensions is as per GB/T 1804-c.
b)Safe mounting distance of circuit breaker
Table 7 Insulation Distance Mounted in the Metal Cabinet (Unit: mm)

Table 8 Minimum Center Distance between Rowed Circuit Breakers (Unit: mm)

Table 9 Minimum Distance between Stacked Circuit Breakers (Unit: mm)