SIB 33

• a. To maintain a bus voltage in distributing stations which will keep a maximum number of feeder regulators within operating range.
• b. To reduce short circuit duty on 4.8 kV or 4.1 kV circuit breakers.
• C. To maintain scheduled bus voltage on receiving station 34.5 kV buses.
• d. To maintain sufficient bank in service capacity to safely carry the station load and meet the normal minimum requirements for receiving stations specified in Station Instruction Bulletin 27, paragraph 9.
• e. To provide for CLEARANCE or OKs TO 
• f. To isolate grounded 4.8 kV circuits or equipment from circuits or equipment which are clear of grounds.

To avoid the inrush of exciting current current which is great enough to cause voltage disturbances to consumers, should a bank be energized from load buses, supplied by another bank

To prevent the unintentional operation of CB

It can lead to wrong assumption that the CB is closed, and result in dropping load

When bank switching is done by ECC, BIS caps may remain on CB control handles of a bank that has been switched out, conversely and bank that is in service will not have BIS caps

Visual confirmation