During maintenance, the output of the system can be supplied power through the bypass breakers in the SSBM or the optional System Maintenance Bypass (SMB). The bypass input and breaker must be rated for the total system load since it must supply all of the system load when on bypass. Manual transfers between the bypass source and the paralleled UPMs are verified make before break.
Operations during transfers to bypass differ depending on the type of transfer: Manual or Emergency. Manual and Emergency transfers function as follows:
Fully Rated Static Switch:
For Manual transfers to bypass, the static switch is not used. During the transfer, CBP is closed and verified and then CBS is opened. For transfers of the load from bypass to the UPMs, CBS is closed and verified and then CBP is opened. The static switch is armed and ready during both types of transfers.
For Emergency transfers to bypass, the static switch is turned on. During the transfer, CBP is closed and verified and then CBS is opened. The static switch turns off after a set time delay which allows the CBP and CBS breakers to complete their transfer.
Communications is required between the SSBM and UPMs in the system for full system operation. System level communications and control are accomplished using a dual redundant network known as PowerNet. PowerNet consists of two independent networks that are connected to each component network node in the parallel system.
Data is always transmitted on both networks simultaneously. Each network node monitors both PowerNets. Failure of one of the two will only result in an alarm condition. In addition, the applications at each node are designed such that messages can be lost on the network without affecting the operation of the system.
Powerware 9315 Parallel Capacity/Redundant System with PHP SSBM | |
| 164201373 Rev. A 092402 |
