CTSM and CTGM Series Manual Transfer Switches

Overview

Some emergency power installations require multiple automatic transfer switches, each feeding a specific load. In many installations where noncritical loads are being served, specifications may call for manual or non-automatic transfer switches. This method is used because operating personnel are present and the loads are not of a critical nature requiring unattended automatic operation.

Because of the less critical function of this equipment, no specific industry requirements have been established. As a result, devices such as double throw disconnect switches have been used. Since the non-automatic transfer switches are part of the emergency power supply system, they should have the same UL 1008 electrical ratings as the automatic transfer switches feeding the more critical loads. In the event of a short circuit, the non-automatic transfer switches must have the same withstand current ratings as the automatic transfer switches and they must be as rugged and dependable.

To meet this need, Caterpillar offers the CTSM and CTGM Series electrically operated, mechanically held non-automatic transfer switches. These units feature the same construction as the CTS Series of automatic transfer switches and are supplied with the same electrical ratings and mechanical features. The manual series is electrically operated by means of push buttons mounted on the switch enclosure or at a remote location. Unlike the above mentioned disconnect switches, the CTSM and CTGM Series offer additional protection by incorporating normal and alternate source voltage sensing relays which will not permit the switch to be manually transferred unless the source to which it is being transferred is at 90% of its rated voltage.In addition, the CTSM and CTGM Series are tested and listed per UL 1008 standards. Double throw disconnect switches are not listed to this critical standard.