Providing robust 300A protection, the Siemens JD3B300 is a 3-pole molded case circuit breaker designed for industrial applications. It features an interchangeable thermal-magnetic trip unit with fixed thermal and adjustable magnetic functions. This unit mount breaker is compatible with Siemens Sentron P4 and P5 panelboards, motor control centers, and switchboards. It is a legacy component replaced by the JD63B300. The JD frame MCCB offers a 65kAIC rating at 240VAC and is fully HACR rated.
What types of equipment are compatible with the JD3B300?
This JD-frame breaker is designed for use in Siemens Sentron Type P4 and P5 panelboards. It is also compatible with Siemens switchboards, motor control centers, and standalone enclosures that accept unit-mount JD-frame breakers.
What wire sizes and materials are accepted by the JD3B300 terminals?
The standard lugs on this breaker accept two 3/0 AWG to 500 kcmil conductors per phase. The terminals are rated for both copper and aluminum wire.
How does the trip unit function on this breaker?
It features a thermal-magnetic trip unit with a fixed thermal element for overload protection and an adjustable magnetic element for short-circuit protection. The adjustable magnetic trip allows electricians to coordinate with downstream devices and prevent nuisance tripping from motor inrush currents.
Does the JD3B300 require a specific mounting configuration?
Yes, this is a unit-mount, bolt-on circuit breaker. It must be bolted directly to the bus or mounting pan in compatible panelboards or enclosures to ensure a secure mechanical and electrical connection.
Can this breaker be used in DC applications?
Yes, the JD3B300 is rated for DC systems. It provides up to 30kA interrupting capacity at 250VDC and 25kA at 500VDC, making it suitable for industrial DC power distribution.
What safety functions does the LI trip code indicate?
The LI designation means the breaker provides Long-Time and Instantaneous protection. Long-Time protects against sustained overloads, while Instantaneous immediately clears high-level short circuits to protect equipment and personnel.
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Customers rate this product 5.0 out of 5 based on 2 reviews.