TRIP UNIT HAVING IMPROVED TRIP ADJUSTMENT INDICATOR AND CIRCUIT BREAKER INCORPORATING SAME

• US 3,831,120 A
• Filed: 11/08/1973
• Issued: 08/20/1974
• Est. Priority Date: 11/08/1973
• Status: Expired due to Term

• Current Assignee: David Barton Powell, Vincent Paul Acampora
• Original Assignee: David Barton Powell, Vincent Paul Acampora
• Inventors: Powell, David Barton, Acampora, Vincent Paul
• Primary Examiner(s): Broome, Harold
• Application Number:
  US05/413,840
• Time in Patent Office: 285 Days
• Field of Search: 335/176,42 200/166M 337/59,129,319,347,360,368,392
• US Class Current: 335/176
• CPC Class Codes: H01H 71/74 Means for adjusting the conditions under which the device will function to provide protection

Abstract

A trip unit for molded case circuit breakers utilizes a tubular extension of its housing to carry a trip adjustment scale which is visible through an opening in the breaker case. An adjustment knob mounted on an adjustment shaft coaxially within the tubular extension is angularly positioned relative to the scale graduations to establish the desired trip setting. The scale graduations may be labeled by indicia imprinted on the breaker case about the opening therein.

Claims

1. An over-current trip unit for use in a molded case circuit breaker, said trip unit comprising, in combination:

A. a housing;

B. means forming an aperture in said housing;

C. a tubular member secured on one end to said housing about said aperture, the other end of said member extending into an opening in the circuit breaker case when said trip unit is operatively positioned therein;

D. means forming an array of trip adjustment scale graduations on said tubular member adjacent said other end, said graduations being visible externally of the circuit breaker case;

E. an adjustment shaft rotatably mounted in said housing and having an end portion extending coaxially within said tubular member;

F. means carried by said end portion facilitating manual rotation of said adjustment shaft; and

G. pointer means carried by said shaft and working to said adjustment scale graduations to indicate the various trip settings of said trip unit.

2. means forming an undercut in said knob extension to impart flexibility to the terminal portion thereof, and

3. a tubular member secured on one end to said housing about said aperture, the other end of said member extending into said cover opening;

4. The trip unit defined in claim 3, wherein said knob is formed with an outwardly radiating extension and said stop extends radially inwardly from said tubular member adjacent said other end thereof, whereby said knob extension abuts either side of said stop to establish said rotational limits.

5. an adjustment shaft rotatably mounted in said housing and having an end portion extending coaxially within said tubular member,

6. A circuit breaker comprising, in combination:

A. a case including a base and a cover;

B. means forming an opening in said cover;

C. an adjustable trip unit located in said case and operating automatically in response to a selected level of over-current to initiate circuit interrupting operation of said circuit breaker, said trip unit including

7. means forming a pointer on said knob working to said adjustment scale graduations to indicate the various trip settings of said trip unit;

and D. indicia carried by said cover about said cover opening to label said scale graduations.

8. The circuit breaker defined in claim 7, wherein said knob is formed with an outwardly radiating extension and said stop extends radially inwardly from said tubular member adjacent said other end thereof, whereby said knob extension abuts either side of said stop to establish said rotational limits.

9. The circuit breaker defined in claim 8, wherein said trip unit further includes means imparting frictional drag to the rotation of said knob and shaft, thereby to discourage spurious shifting of the manually established trip setting.

10. The circuit breaker defined in claim 8, wherein said trip unit further includes:

11. The circuit breaker defined in claim 8, wherein said trip unit further includes:

12. The circuit breaker defined in 6, wherein said scale graduations are in the form of notches formed in the edge surface of said tubular member other end, and said pointer means is in the form of a radially extending groove formed in the exposed surface of said knob.

13. The circuit breaker defined in claim 12, wherein the width of said pointer groove conforms to the width of each of said scale graduation notches.

14. The circuit breaker defined in claim 13, wherein said knob is formed having an outwardly radiating extension terminating in contiguous relation to the inner surface of said tubular member, said pointer groove extending to the termination of said knob extension.