Application Engineering

Please read the Warranty Statement carefully before proceeding with any design or ordering materials or labor.

These documents are in PDF format. To view them, you will need Adobe Reader® software.

The bibliography gives a number of useful references for codes and standards.

Alternative Power System Arrangements features a number of alternative power systems for Basic Standby, Redundant Standby, Automatic Priority Selection, Sequential Prime Power, Dual Utility with Standby Generator and Automatic Transfer Switch with Dual Remote Switches.

The schemes are illustrated with one-line diagrams and descriptions.

Requirements and Recommendations:

• Segregation of essential and non-essential load distribution is required by code in some regions.
• In a basic standby scheme, the transfer switch connects either utility or standby generator set power to the essential loads only.
• In a redundant standby scheme, the utility line is backed up by a generator set, which is in-turn backed up by a further generator set. An enhancement of this scheme is where the second generator is smaller and backs up critical loads only.
• Automatic Priority Selection schemes use three transfer switches and two generator sets and allow either of two generator sets to be connected to the critical load during a power outage. In event of generator failure, critical load is supported by the alternative generator and load shedding signals are sent to less critical loads if required.
• In a Sequential Prime Power scheme, no utility source is present. The load is supported by three generator sets running at alternate times to provide power to the load. Two transfer switches are used. Failure of any generator set is addressed by the transfer switch logic and an alternate generator is started and connected.
• Dual Utility with Standby Generator schemes use two transfer switches to allow utility-to-utility transfer and utility-to-generator set transfer. Failure of one utility supply results in connection of the load to the remaining healthy utility. If both utility supplies fail, the load is connected to the generator.
• Automatic Transfer Switch with Dual Remote Switch schemes use an automatic transfer switch with a number of non-automatic transfer switches. The automatic switch provides utility failure and utility-to-generator changeover. The more economical remote, non-automatic transfer switches respond to transfer / retransfer signals from the automatic transfer switch and provide power to their respective loads.

For information regarding your application contact your nearest distributor.

To comment on any of this documentation please use our feedback form.