Distribution Recloser Timing

[wbd]

What are some of the dead times people are using for reclosers? For example, we are using 0.5, 1.0, 5.0 seconds.

 

[busbar]

wbd, could you tell us the application? Single or tapped loads? In general, 'instantaneous' reclosing (with breaker mechanical delay only) on the first shot is fairly common. Some prefer changing trip characteristics after the first shot. It depends on your operating philosophy, load characteristics and tradeoffs between service continuity and acceptable stresses to the system. Reclosing is usually preferable for overhead circuits, but is of little desirability on shielded cables. ABB’s Applied Protective Relaying text or GE’s Art and Science of Protective Relaying has some statistics for various fault types. Microprocessor-based protection can offer some sophisticated and dynamic schemes these days. Reclosing is the next best thing to having as little outage time as possible, in exchange for limited damage to equipment. It usually boils down to 'what will be most profitable over time.’

 

[wbd]

Busbar,
This is an application on overhead distribution system (4 wire multi-grounded) 4160/2400. The reclosers are being installed to protect the three phase backbone while all side taps are fused. The recloser's trip curve is set to allow the side tap fuses to clear without affected the main line.
Some discussion has occured on what to set the dead times between reclosing. Right now we're set as follows:
Fault - open wait 0.5 secs, reclose
still faulted - open wait 1.0 secs, reclose
still faulted - open wait 5.0 secs, reclose
still faulted - open and lockout
I was wondering what other utilities are using for dead times?

Thanks for replying
wbd

 

[jnims]

The dead times you chose can be affected by the upstream protection. If the upstream device is an electromechanical relay, you have to be concerned with the disk travel of the relay. Increasing the dead times can improve coordination. Some typical times shown in the Cooper manual on distribution protection are

Inst, 2.0, 2.0
2.0, 2.0, 2.0
2.0, 2.0, 15.0

 

[wbd]

Thanks jnims.
The upstream protection is a fuse (k link) to back up the recloser in case of failure. The recloser TCC fits in between the side tap fuse curves and the backup fuse curves. The recloser is looking at the 3 phase backbone and set to give the side tap fuses time to clear any side tap faults.

wbd