140MG-G8P-C70 Allen-Bradley Motor Circuit Protector

Model: 140MG-G8P-C70

Brand: Allen-Bradley

Product Series: Bulletin 140MG

Product Type: Motor Circuit Protector (MCP)

UPC: 885630441993

Frame Size: G Frame

Rated Operational Current: 70 A

Number of Poles: 3

Protection Type: Magnetic only

Magnetic Adjustment: Adjustable, nine cam settings

Magnetic Pickup Range: 210–770 A

UL Interrupting Rating: 65 kA at 480V AC

Published Interrupting Rating Range: 35–65 kA at 480V AC

Assembly: Factory assembled

Lifecycle Status: Active

Product Introduction

 

The Allen-Bradley 140MG-G8P-C70 is a three-pole motor circuit protector from the Bulletin 140MG family. It is designed for motor branch-circuit applications where magnetic short-circuit protection and manual switching are required.

 

This model has a rated operational current of 70 A and uses an adjustable magnetic trip mechanism. Rather than relying on a thermal-magnetic trip unit, it responds to high-current fault conditions through its magnetic protection function. This makes it different from a conventional motor protection circuit-breaker that combines thermal overload and magnetic short-circuit protection.

 

The 140MG-G8P-C70 is intended for use as part of a coordinated motor controller assembly. In a typical arrangement, the motor circuit protector provides branch-circuit short-circuit protection, while a separate overload relay provides motor overload protection. The selected combination must meet the applicable short-circuit coordination and installation requirements.

 

Rockwell Automation identifies this catalog number as an active product in its Bulletin 140MG range.

 

One of the defining features of the 140MG-G8P-C70 is its adjustable magnetic pickup setting. The trip adjustment uses nine cam positions, allowing the magnetic response level to be selected for the motor circuit.

These settings are particularly relevant when coordinating the circuit protector with a motor's starting characteristics and the downstream contactor and overload relay.

The selected setting must provide adequate short-circuit protection while avoiding unwanted operation during normal motor starting. The correct value should be determined from the motor data, starting method, available fault current and the applicable coordination tables-not simply chosen from the motor's rated current.

The 140MG-G8P-C70 provides magnetic short-circuit protection rather than combined thermal and magnetic protection.

Short-circuit protection

When a high-current fault occurs, the magnetic trip mechanism responds according to its selected pickup setting and interrupts the affected motor branch circuit.

No integrated thermal overload release

This model does not provide the thermal overload function found in thermal-magnetic motor protection circuit-breakers. A separate overload relay or another suitable overload protection device is required for motor overload protection.

Manual circuit switching

The device also provides a means of manually switching the motor branch circuit as part of the motor controller arrangement.

This distinction is important when comparing the 140MG-G8P-C70 with products such as the 140M-C2E-B16. Both belong to Allen-Bradley's motor protection product range, but their protection functions are not interchangeable.

The 140MG-G8P-C70 is intended for use in combination motor controllers rather than as a standalone motor overload protection device.

A typical motor starter arrangement may include:

• Motor circuit protector: Provides magnetic short-circuit protection and manual switching.
• Contactor: Controls the motor's normal starting and stopping operations.
• Overload relay: Provides protection against sustained motor overload conditions.

The specific combination depends on the motor rating, supply voltage, starting characteristics and required short-circuit rating. Rockwell's technical documentation includes combination and selectivity information for the Bulletin 140MG family.

A useful point when identifying this model is the distinction between its 70 A rated operational current and the G-frame designation.

The 70 A value identifies the product's rated operational current. The G-frame designation identifies its frame family; it should not be interpreted as a statement that the device has a 125 A operational current.

Likewise, the 65 kA UL interrupting rating at 480V AC describes its short-circuit interrupting capability under the specified rating conditions. It is not a continuous current rating and should not be confused with the 70 A operating-current value.

 

 

Typical Applications

• Three-phase industrial motor branch circuits
• Motor control centers and starter assemblies
• Industrial machinery with higher-current motor circuits
• Contactor-based motor control panels
• Applications requiring adjustable magnetic short-circuit protection
• Coordinated motor controller installations

1. Is the Allen-Bradley 140MG-G8P-C70 a motor protection circuit-breaker or a motor circuit protector?

It is a Motor Circuit Protector (MCP). Its protection function is magnetic-only short-circuit protection. It does not include an integrated thermal overload release.

2. Does the 140MG-G8P-C70 provide motor overload protection?

No. A separate overload relay or another suitable motor overload protection device is needed to protect the motor against sustained overload conditions.

3. What is the rated current of the 140MG-G8P-C70?

Its rated operational current is 70 A. This is distinct from the G-frame designation and the magnetic pickup setting.

4. Is the magnetic trip current adjustable?

Yes. The model uses nine magnetic adjustment positions, with published pickup values ranging from 210 A at setting A to 770 A at setting I.

5. What is the interrupting rating at 480V AC?

Rockwell lists a UL interrupting rating of 65 kA at 480V AC. The product description also identifies a 35–65 kA range at 480V AC, depending on the applicable rating conditions.

6. Can the 140MG-G8P-C70 be used as a standalone motor controller?

It should not be treated as a complete motor controller or as a standalone motor overload protection device. Rockwell specifies this product family for use in combination controllers, with the appropriate contactor and overload protection arrangement.

7. Is the 140MG-G8P-C70 still an active Allen-Bradley product?

Yes. Rockwell Automation currently identifies the 140MG-G8P-C70 as an active product.

The catalog number 140MG-G8P-C70 identifies the 70 A G-frame magnetic-only motor circuit protector. Its UPC is 885630441993.

When sourcing this component, check the complete catalog number rather than relying only on the 140MG family name. Other 140MG variants may have different current ratings, frame configurations or factory-installed accessories.

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