621.317SchaL Schmelcher, Theodor Low-voltage handbook: technical reference for swinchger, controlgear and distribution systems/ By Theodor Schelcher; tr. By Les J. Croyston.-- Berlin: Siemens Aktiengesellschaft, 1984. 347p. : ilus. : 24cm. It is published with the intention of of assisting the reader in the selection and application of siemens products. "Definitions":p. 326-344 ISBN 3-8009-1396-8