Allis-Chalmers D and F switchgear - closed door racking modification

10/01/2006 - Volume III - Issue II

Allis / Chalmers / Siemens manufactured type D and F medium-voltage switchgear from 1958 to 1990. This gear utilized air magnetic breakers that were typically manually racked via a lever while the cubicle panel door was open (see below photo).

Siemens offers a cost effective field modification to convert D and F gear to a closed-door, remote rack design. This modification provides a cost effective solution to keep operators clear of the arc flash zone during breaker racking.

Before: Original floor mounted lever racking, commonly used on D and F gear, required operator to stand in front of the breaker with panel door open.

The field modification consists of a floor mounted screw racking device and a breaker-mounted bracket to interface with the floor-mounted screw device. Both additions are easily installed on existing units and can be provided for 5kV, 7.5 kV, and 15kV ratings, from 1200A through 3000A.

These additions allow end-users to either have closed door manual racking or have closed door remote racking.


The closed door remote racking option requires the above mentioned cell and breaker additions as well as a minor front panel modification to accept a torque-regulated motor. The motor can be moved from one cell position to the next, thus only one motor device is required.

After: Following the field modification, the circuit breaker can be racked in and out while the operator stands outside of the arc flash zone.

Mailing address

Siemens Industry, Inc.

7000 Siemens Road

Wendell, North Carolina 27591

United States