c) Multicircuit constant current type is depicted by a circuit
diagram in Figure 40. This type of rectifier is designed to provide a
small, constant current in the order of 100 mA to a single anode. As the
resistance of the internal resistor is high when compared with the extern
circuit resistance, the output current is controlled by the value of this
resistor. The output potential will vary up to the line voltage to suppl
the specified output current. In this type of circuit, the structure is
supply. Due to problems associated with stray currents and the possible
presence of high voltages external to the rectifier units, the use of thi
type of rectifier is not recommended.
Several standardized rectifiers have been developed for
commercial applications such as natural gas and electrical distribution
system protection. The use of a standardized unit allows for economy of
production and reduction in overall cost of the unit as well as the
installation and maintenance of the unit. Where a large number of simila
capacity units are to be used, the selection of a standardized type of
rectifier should be considered.
6.5.3 Rectifier Selection and Soecifications. Rectifiers can either be
selected from "stock" units or can be custom manufactured to meet specifi
electrical and site-related requirements. Many features are available
either as "add on's" to stock units or in custom units.