Ruggedness

The mechanical construction of the type SQ cutout is rugged and strong : it is designed to withstand the interruption forces of heavy fault currents and the typically forceful closing-in by linemen.
The upper contact and the hinge are attached to husky steel supports. Both supports and the mounting insert are permanently anchored into cavities in the insulator with inorganic cement, which does not deteriorate or absorb moisture, The cement will not shrink to loosen the inserts nor swell to put stress on the insert cavities of the porcelain. In fact the cement retains a slight resiliency to absorb part of the shock of the interruption forces.
This cemented construction eliminates the conventional steel bands around the top, bottom, and center of the insulator. Such bands produce mechanical stress concentrations at these three points; their thin insulation coatings are subject to damage due to mishandling on installation and to deterioration with time and weather, and there is an eventual loss of birdproofing and a lessening of the leakage distance.

Superb Current Transfer

The fuse tube is held at the upper contact by a self-aligning spring-loaded detent-type latch. The detent is heavily silver clad and features embossed surfaces for built-in wiping action - resulting in minimum electrical resistance between the upper contact and the silver-clad fuse tube cap.
The heavily silver-clad lower contacts also feature embossed surfaces for built-in wiping actions, and are backed up pre-stressed stainless-steel loading springs for efficient current transfer between the contacts and the silver-clad fuse tube trunnions.
these specially designed high-pressure upper and lower contacts, featuring built-in wiping action, assure superb current transfer - even after the contacts have been exposed to the atmosphere for an extended period of time.

No Fuse-Link Breakage

The Type SQ Cutout has been engineered to prevent to fuse link breakage when the fuse tube is slammed shut. Instead of the conventional method of using the fuse link directly to restrain the toggle, a flipper is used as a lever to restrain the toggle.
During closing, the peak force action downward on the top of the fuse may reach sixty pounds. However, the high reduction ratio of the Type SQ lever system allows the impact to be absorbed before it reaches the fuse link.
This protection of the fuse link from ht impact forces of closing does not impair the split-second flip-out of the fuse link when severed by current. (Flip-out is caused by the spring-loaded flipper and does not rely on the force of the exhaust or collapse of the toggle)

Positive Mechanical Action

The Type SQ Cutout features :
- Easy tube insertion;
- Positive alignment when closing;
- Completely reliable dropout, regardless of fault-current level

To make the fuse tube easy to install under all conditions, wide conspicuous ears on the hinge engage substantial trunnions on the fuse tube. Careful steering or manipulation is not required to hang the tube in the cutout.
Yet this ease of insertion has not compromised the sureness of closing - from any angle and under adverse conditions of light and weather. Trunnion pockets in the ears of the hinge restrain the fuse tube from tilting right or left as it is swung closed. During the closing operation. the fuse tube is steered by the broad guiding surfaces at the hinge. As the tube approaches the upper contact, it is further controlled by load buster attachment hooks, and, at the end of the closing stroke, the fuse wipes in and seats positively in the detent-type latch.
To ensure dropout of the fuse tube after circuit interruption - even after long periods of inactivity - the Type SQ Cutout utilizes a high-speed spring-loaded flipper, which in addition to whipping out the severed fuse-link cable. provides an impaction action to aid in the collapse of the toggle system. The upper contact springs also contribute to toggle collapse by pushing the fuse down and out into the open position.