NEMA Standard Bolt-On Miniature Circuit Breaker
Review
Description
General Introduction
This Miniature Circuit Breaker supply protection and circuit control against overload and short circuit.
It has 3KA & 4.5KA short-circuit capacity, rated insulating voltage 120 and 240V and used for circuit of AC 50/60Hz.
It is easy mounted on QO load center, NQ and NQOD panelboard or OEM mounting bases, can be widely used in House, Office, Commercial Complex and industrial installation, for switching, control, protection and regulation of electrical circuits, also in switchgear panels, railways and marine application.
It stipulated in NEMA Standard AB1. Mechanical system stipulated in International Standard IEC 60947-2.
Operating Mechanism
This one-, two- and three-pole thermal-magnetic circuit breaker have an overcenter, trip-free toggle mechanism with quick-make, quick break action and positive handle indication. The tripping mechanisms in two-and three-pole circuit breakers operate such that an overcurrent on any pole of the circuit breaker will cause all poles of the circuit breaker to open simultaneously. Each pole has an individual thermal-magnetic trip element calibrated for 40°C ambient temperature.
Trip Indication
This miniature Circuit Breaker have Visi-Trip trip indication, which provides a visual indication that the circuit breaker has tripped and interrupted the circuit. When the circuit breaker has tripped, the handle assumes a center position and the red Visi-Trip indicator appears in a window in the circuit breaker case. The Visi-Trip indicator is only visible when the circuit breaker has tripped. Trip indication immediately distinguishes the circuit from any other circuit which is merely in the on or off position. The circuit breaker can be reset by pushing the handle to OFF and then to ON.
Ratings
When designing an electrical distribution system, overcurrent protective devices are generally selected based on performance requirements. Factors influencing this selection include system voltage, continuous current, interrupting rating, and frequency.
Voltage Rating
The circuit breaker must have a voltage rating greater than, or equal to, the system voltage. When a circuit breaker clears an overcurrent, it is done in two steps. First, the current sensing system identifies the overcurrent and releases the tripping mechanism. This results in a parting of the contacts. The circuit breaker must then extinguish the voltage arc across the contacts. If the circuit breaker has the correct voltage rating, it can efficiently extinguish this voltage arc
Main Specification
Rated Current : 10A, 15A, 20A, 25A, 30A, 35A, 40A, 50A
Trip Curve
Tripping Curve : Type C
Dimension
Pole
Poles : 1P, 2P, 3P
Cross-Section
Mounting
QO load center NQ and NQOD panelboard
