Description

S&C 11kV Cut Out, c/w Earth Spigot. Cut Out Supplied with NEMA specifications cross arm bracket and reflective tape on the fuse tube. Two only 100mm. long mounting bolts and two only 150mm long mounting bolts for the NEMA bracket are included.

2.0 11 kV Cut Out Fuse Unit Features

The S&C 11 kV Cut Out Fuse offers users some unique performance features as follows:

2.1 Interrupting Ability
Until recently, the 89032-R10 Cut Out Units have had a fault interrupt rating of 12kA (3 Shot) and 16kA(1 Shot). As a result of product development, S&C have tested and proved that the 89032-R10 unit will clear 3 shots at 16kA. The S&C 89032-R10 is unique in its ability to be able to meet this rating. The enhanced fault rating is extremely significant as the unit provides a level of future proofing which handles the level of available fault current increasing on the distribution network. It will also delay expenditure on replacement of 11 kV cut outs as the higher fault rated units will provide prolonged unit in service life.

2.2 Non Hygroscopic Tube
The fuse tube on the S&C unit is manufactured from a non hygroscopic material (ie will not soak up water). This is a significant feature as if the drop out is left open or "dropped out" for a period of time, often the tube will fill up with rain water or be exposed to condensation. In this type of case, when the linesman comes to refit the fuse element it cannot be inserted into the fuse tube - essentially the fuse tube is a throw away. If put back into service with the tube liner swollen, there is a high risk of the drop out "hanging up" or not dropping out. Hang ups in the event of a fault create the potential for extensive and costly transformer or cable damage. The liner on the inside of the S&C 89032-R10 will not swell up as a result of contact with water, providing more reliable performance.

2.3 Earthing Arrangement
All S&C Cut Outs supplied by Electropar will be accompanied by an earthing stirrup nut and spring washer. The bolt thai attaches the trunnion to the porcelain body of the Cut Out will allow the stirrup to be bolted to the Cut Out. This solution keeps the head of the temporary earth set from encroaching inside the MAD when temporary earths are applied.
All S&C Cut Out boxes will contain the stirrup, relevant fastenings and instructions for installation of the new arrangement. The 89032-R10 S&C Cut Out fully complies with the NZ Electrical Regulations in this respect.

2.4 Fuse Tube Flipper and Fuse Link Exit

The flipper at the bottom of the fuse tube on the S&C 89032-R10 unit is designed so that the fuse link always exits in the centre of the tube. This is important as the tube material is ablative, ie, some of the fuse tube material is used up every time the Cut Out operates as a result of a fault. If the fuse link does not exit the fuse tube in the centre, one side of the tube will be used up more quickly than the other (in a fault situation) limiting the life of the fuse tube. A fuse tube that does not allow the fuse link to exit the fuse tube in the centre will cause the fuse tube ablative liner to be used up more quickly, increasing the potential for the Cut Out to fail in the event of a fault thereby decreasing its in service life
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2.5 Cut Out Fuse Trunnion Cradle
The cradle in the S&C 11 kV Cut Out expulsion fuse is designed so that there is the minimum of sideways movement when the fuse tube is closed into the fuse base. It is almost impossible when closing the fuse tube in the S&C Cut Out to force it outside the loadbuster hooks at the top of the unit. This is a real issue for field staff as when they are standing on a ladder closing in the outside phase, if the tube was forced outside the loadbuster hooks it would be jammed there, arcing. This is a potentially very dangerous situation that at worst could result in personal injury and at best force the control room to drop the feeder so that the problem can be sorted.

2.6 Fuse Tube Cap
The cap on the S&C fuse tube is not knurled to aid handgrip: it is smooth. It is designed this way so that the field staff will pull out their spanner and tightening the cap instead of relying on hand tight. The force of the tightening with a spanner will break the oxidation layer in the thread and alleviate the potential for a hotspot on the Cut Out's source side contact. A hot spot at the top of the tube has the potential to damage the fuse link which is secured by the cap, weakening the link if it is manufactured from tinned copper. In this event, the fuse link could fail early in its service life and force the network operator to replace the fuse link prematurely.

2.7 Silver Contacts
All electrical contact points on the S&C Cut Out are silver to silver. In recent analysis, the S&C unit was shown to have a silver plated thickness three times greater than any other unit available in NZ.

2.8 Interchangeability
Electropar confirms that the other most commonly used Fuse Tube and Link Break Tube will fit the S&C Porcelain Fuse Carrier.

2.9 Life Expectancy
Life expectancy for cutouts fuses is very dependent on local environmental conditions and number of operations in service. In hot dry climates, a Cut Out could last 50 plus years. In a harsh coastal salty climate, a Cut Out could last as little as 5 years. In an averagely polluted NZ Power Company environment we would expect an S&C Cut Out to last somewhere in the region of 15-25 years.One important point to note is that the fuse tube itself is rated for 3 only 100% capacity expulsions (16kA). This is not unique to S&C, as all Cut Outs are rated similarly. After that, the fuse tube should be replaced. In practice in the NZ Power Company environment, full rated expulsions are very rare, most faults are of small magnitude and hence the fuse tube will provide a great many successful operations.

2.10 Connection to Aluminium/Copper Conductors
The S&C Cut Outs are supplied as standard with PG clamps for connection of copper and aluminium stranded or solid conductors to the unit. The PG clamp can accept a range of conductors from 10mm2 to Dog/Weke/120mm2. The PG Clamps supplied with the S&C Cut Out are tinned to suit copper or aluminium. Electropar offers the Ring Connector for attachment of copper or aluminium terminals as an option.

2.11 Test Certification
S&C Type XS Cut Outs meet the requirements of ANSI C37.41 -1981. Performance of the Cut Outs is detailed in S&C Bulletins 351-30 and 351-300. Detailed test reports are available on request.

2.12 Provision for Isolation of Large Loads
The S&C Cut Out is not a load break device. However, it can be utilised to break load when it is operated with a Loadbuster tool. Many power companies have a couple of Loadbuster tools available to field staff that are booked out to jobs as and when they are required.