All variable frequency drives (VFDs) are to be furnished complete with a manually operated, single cam switch style bypass system. Two and three contactor type bypass systems are not allowed.
The manually operated bypass system is to be the IBYSS ® system as manufactured by ACI, Bradenton, Florida. The system is to have 4 positions: "LINE", "OFF", "DRIVE" and "TEST".
"LINE" (BYPASS) position completely bypasses the drive. All power is to be directed straight to the application so the application receives full line power. No power is to be on either the drive input or drive output terminals. In the “LINE” position the VFD is physically and electrically isolated, allowing the VFD to be safely repaired or replaced.
"OFF" position disconnects all power to both the drive and the application.
"DRIVE" position connects the drive to the incoming power and to the application.
All drive functions are to be available to the application when in the "DRIVE" position.
"TEST" position connects the incoming power to the input of the drive. No power is to be allowed from the drive to the motor application.
IBYSS ®system shall be packaged in a separate enclosure from the VFD. The IBYSS ®
system shall be furnished complete with a terminal strip for field wiring connections. The degree
of environmental protection furnished by the enclosure shall be Type 12, Type 4 or Type 4X.
The IBYSS ® system is to be equipped with two auxiliary contacts.* Contacts must be suitable to
signal Building Automation Systems (BAS, DDC), PLCs or other logic / indicating devices.
* 1 Contact closes in the "LINE" position
1 Contact closes in the "DRIVE" and "TEST" positions
The IBYSS ® system is to be specified, sized and installed per ACI's recommendations.