The switchboards installed in this type vessel are of rigid self-supporting construction providing only a minimum of equipment with respect to circuit design.  The individual feeder circuits are not provided with disconnect switches but are fused only.  Neither Interior Communication or Fire Control Circuits are grouped to be controlled from common switchboards.  
March, 1946
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A. Descriptive Page Number
  (a) Introduction
  (b) Description
  (c) Conclusion
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          (a)  Introduction  
          The scope of this report is to present in a concise manner, the German practices incorporated in the construction of the auxiliary power switchboards.  For detailed information regarding construction and circuit details. reference should ben made to the German Instruction Books, "Beschreibung und Betriebvorschrift für E-Maschinen, Haupt und Hilfschalttafeln", (Descriptive and Operational Data for the Electric Machines, Main and Auxiliary Switchboards), and to the applicable detail reports on the various components.  
          (b)  Description  
          The voltages controlled by these switchboards are 110-170 V. D.C. for main and auxiliary power and regulated 110 V. D.C. for ship's lighting, I.C. equipment and various other purposes.  The number of panels incorporated in a board varies depending upon its function.  
          The switchboards are of rigid, self-supporting angle iron and flat bar arc welded construction, hinged and bolted front and top covers, bolted perforated sheet steel side and rear covers.  The hinges are of continuous Veeder Root design (Piano hinge).  No attempt is made to isolate the various sections, bus, fuse, metering, etc. from each other.  The units are drip-proof and are designed for natural ventilation.  Supply and distribution leads are generally led in either the top or bottom at the rear of the units.  The switchboards are mounted on bonded rubber mounts in compression for shock protection.  Components are readily accessible and removable from the structure.  No effort has been made to keep resistor units as high in the structure as possible to minimize the heating effect on other components.  Circuits do not appear to be segregated into vital and non-vital classifications and identification of cable and circuits is kept to the minimum consistent with the German method of presenting the systems to the operating personnel.  (The German method of presenting the various systems will be discussed in detail in Report 2G-9C-S28 on Type IXC vessels).  
          Ammeters and voltmeters are provided for measuring the input current and voltage of the 110-170 V panels and for measuring the output voltage and current of the voltage sensitive relay actuated regulator provided for  
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  the regulated 110 V D.C.  There is no provision made for using the installed voltmeter to check ground voltages.  Controllers in the main control switchboard are manually operated being provided with levers for vertical motion.  Controllers are mounted directly behind the front panel.  Socket type, porcelain body, sand filled fuses with blown fuse indicators are used throughout.  Tube type terminals soldered to the cables are bolted to terminal board or buses as required.  Riser buses are installed on either side at the rear of the structures to which the individual feeder circuits are connected either by cables or by copper bars.  A thin coat of red glyptol-like paint is applied to the copper bars to minimize corrosion.  Application of silver painted contact surfaces is sporadic.  Insulating materials are kept to a bare minimum, none of which appears to be molded to the copper bars.  
          Inspection of the bus work indicates that labor was considered secondary to copper conservation as is evidenced by the following example.  
          Where the cross sectional area and geometry of a connection bar for a given maximum current did not permit drilling for the desired size connection bolt and still provide sufficient surface contact, the Germans frequently welded "ears" to the bar on both sides at each end in way of the contact area.  
          In general, greater current densities are permitted for bus and connection bars and cables than is current USN practice.  
          Neither I.C. nor Fire Control Circuits are grouped to be energized at common switchboards.  Considerable disadvantage occurs from this practice in that if in the control room the operating personnel are in a hurry to perform their various duties, there would be a tendency to get in each other's way in moving about to actuate the I.C. and F.C. circuits.  
          (c)  Conclusions  
          The German need for economy in labor and critical materials is reflected in the design and manufacture of these switchboards.  There is nothing of interest in the structures as a whole.  The salient features of the various components will be discussed in detail under the applicable "S" group reports.  
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