Dead Break Elbows v Load Break Elbows

Elastimold Connectors

Elastimold

Dead Break & Load Break Connectors

200 Amp Loadbreak Elbows

200 Amp Deadbreak Elbows

600 Amp Elbow Connectors

 

Screened separable connectors, cable splices and elbows are used in the underground medium-high voltage electrical distribution industry to attach cables to equipment (such as a transformer or switchgear) and to attach cables together (cable splice or cable joint) in trenches or man-holes.

A dead-break elbow requires the cable to be “dead” in order to be detached or attached and is typically rated for 600A. A load break elbow can be attached or detached live or under “load” and is typically rated for 200A.

As you can see, one difference between elbows is the increased current rating of a dead break elbow, but there are various other differences as well.

 

Standard Interfaces for Separable Connectors & Equipment Bushings

IEEE Standard 386 defines the specific interface dimensions that 200 Amp and 600 Series elbows, inserts, junctions, equipment bushings and any mating components must conform to ensure interchangeability. 

 

  • Load Break Elbows


A load break elbow when used with a hot stick can be connected or disconnected at high voltage under load, but can only be used with up to a 250kcmil cable. At 100% insulation level, a 250kcmil is good for 345A in underground duct, so you would be de-rating your system by using a 200A elbow with a 250kcmil cable, but they are still widely used due to the flexibility given to the high voltage distribution system at the equipment.

Think about it…if you had a critical application where power disruptions were extremely costly and maintenance was required on up-stream equipment in, let’s say a non critical area, this product would be great. You could disconnect the load without disturbing the critical portions, perform the maintenance and then reconnect it. Just make sure to take safety precautions, making and breaking electrical connections under load is very dangerous. The load break elbow is typically not used in man-holes, because it does not allow expansion like the dead break elbow. The construction of the load break elbow does not allow it to be connected to other elbows, but the dead break does.

Elastimold 200Amp Loadbreak Elbow Connectors

Elastimold 200 Amp Loadbreak Connectors provide a convenient method to connect/disconnect cable and equipment on power distribution systems.

Loadbreak elbows include provisions for energized operation using standard hotstick tools, allowing loadmake/ break operation and a visible disconnect. Components can be isolated with insulated caps, plugs and parking bushings. Optional accessories allow system grounding, testing, bypass, surge protection and current limiting fusing. Additional connecting points and taps can be provided by use of junctions or feed-thrus.

Pictured : Elastimold 200Amp Loadbreak Elbow Connectors

Elastimold-200Amp-Loadbreak-Elbow-Connectors


 

  • Dead Break Elbows


A dead break or “hammerhead” elbow can only be disconnected when not under load, this is because you need to actually unscrew a pin to detach it. It would be pretty tough to unscrew the pin with a hot stick and the arc from the disconnected load, if under load, would be pretty substantial. A dead break elbow allows an increased current rating (up to 600A) and can be used on basically all cable types. At 100% insulation level a 750kcmil cable is rated 610A in underground duct.

When would you use a 750kcmil? In most non-utility cases you would design or install sets of 500kcmil or smaller if you needed more than one 500kcmil could handle. Even from a 1200A breaker, two sets of 500kcmil per phase would be sufficient for distribution (about 1000A), if the load was even that high. Most of the time you set the relays down to the actual load in order to limit the copper used. A dead break when used in man-holes for splicing cables allows the flexibility of connecting more than two cables together as well as future expansion if required.

Say another building was added that needed power, you could just connect that building to the existing array of dead break elbows. This also works great when temporary power is needed for construction or even if the circus is in town and they need medium voltage (it happens!). They can pick up power from the man-hole with the dead break elbows or from a piece of equipment with dead break elbows. I’ve heard that ships are now starting to use medium voltage shore power, I wonder what kind of connections they use.

A dead break elbow still provides flexibility during maintenance it just requires a brief outage to allow the cable splice to be broken. This high voltage outage could be scheduled at an off-peak time or after ensuring that all back-up systems were already running and/or transferred to another source such as a generator. I wouldn’t trust a UPS alone in this case unless it was connected to a second source of power like a generator.

The amount of time to disconnect the splice and coordinate the outage would cut it real close. Deadbreak elbows are fairly large, so make sure to check the space restraints of the location you are installing them. If you do run into a space problem, there are various other seperable splices on the market that may be suitable, check with the manufacturers.

 

Elastimold 600Amp Deadbreak Elbow Connectors

600 Series deadbreak elbows, straight receptacles, junctions, vault stretchers and accessories are used to connect equipment and cable on primary feeder and network circuits. Designs accommodate large conductors and feature bolted connections and deadfront modular construction for maximum reliability, performance and versatility.

De-energized connectors can be quickly and easily connected and disconnected using standard hand tools and equipment in accordance with accepted operating practices. Optional accessories allow visible external separation, bypass, isolation, dead-ending, grounding and testing as well as adding taps, surge arresters and circuit protection.

Pictured : Elastimold 600Amp Deadbreak Elbow Connectors

Deadbreak Connectors

 

Elastimold Connectors

 

Video : 15kV High Voltage Dead Break Substation Jumpers - Improper Cable Termination & HiPot Testing. ATI was sent some temporary 15kV substation jumpers where the Dead Break Elbows were improperly terminated.ATI inspected and HiPot tested the high voltage 15kV cables. The video shows the details and also shows proper cut-back of a 4/0 15kV Temporary Substation Jumper Cable.

Elastimold - HV High Voltage Loadbreak & Deadbreak Connectors

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Adobe Load Break Elbows 200Amp - 3M