The battery charger (DC Power system) shall have two voltage settings namely float & equalize, selectable by a panel mounted switch. It shall comprise an isolation transformer, an SCR bridge rectifier, control circuitry, metering & protection.
Wherever possible, plug-in modules shall be used for easy removal and insertion. All components shall bear the manufacturer's identifying markings and, except for electronic circuitry and transformers, be commercially available in major centers. All components shall be suitably sized to carry the full load continuously under all stated environmental conditions. The unit shall be convection cooled (no fans). A transformer shall in all cases isolate the DC from the AC source. The unit shall be housed in an EEMAC1 wall mount or floor mount sheet steel cabinet having a hinged door or doors with "quarter-turn" closing device requir- ing the use of a tool to open. The unit shall be finished with ASA61 grey baked enamel over primer.
The AC shall be rectified by an SCR bridge rectifier mounted on extruded aluminum heat sinks. The SCR firing shall be controlled electronically.
The SCR firing control circuit shall be of the plug-in type and supported only by an appropriate edge card connector with card guides for ease of insertion and removal. The circuit shall limit the current, and regulate the output voltage to +/- 1/2% of setting for any combination of +/- 10% variation in input voltage, O to 100% variation in load, and +/- 5% variation in line frequency without the use of internal or external dummy loads. The float and equalize voltages as well as the current limit shall be adjustable my means of individual multiturn potentiometers mounted on the circuit board and adequately identified. The PCB shall be adequately coated with an appropriate varnish. PCB components shall be identified by means of a silkscreen for ease of repair and trouble shooting.
The following instruments and controls shall be included as a minimum:
The units shall be Cigentec inc. type C-P.