KEPCO MBT Series - Manual (Page 118)

4-12
MBTSVC111609
The main function of Relays and Flags Board A2 is to deliver all the flags necessary for Digital
Control Board A3 via Mother board A5. For MR and MGR option units, this board also contains
the circuitry to control the opening and closing sequence of the output/polarity reversal relays
and the sensing leads relays.
Digital Control Board A3 receives digital commands from either the front panel (via Front Panel
Board A8) for local operation, or from either an internal “G” option or an external controller over
the two-wire IEEE 1118 bus for remote operation. This board generates the voltage and current
Reference Voltage signals which are sent to Analog Control Board A1 to control the power sup-
ply output. This board also converts the analog output current and voltage into digital signals for
transmission to a controller via the IEEE 1118 bus. In addition, this board controls Front Panel
Board A8 which provides the interface between the front panel VOLTAGE and CURRENT con-
trols, keypad, status indicator LEDs and LCD display.
Auxiliary Power Supply Board A4 contains an auxiliary transformer, five bridge rectifiers, and
two +5V IC power supplies used to generate supply voltages (±21V, +10.5V, +5V (2), and
+12.5V) for the circuitry on Boards A1, A2, A3 and A8. These voltages are provided via Mother
Board A5 which serves to interconnect boards A1, A2, A3, A4, and A8, except for the isolated
+5V sent directly to A3 for isolated input/output circuits.
4.3 DETAILED CIRCUIT DESCRIPTIONS
The following paragraphs provide detailed circuit descriptions of the MBT Series Power Supply
Circuits. Figure 4-5 shows the location of major components within the power supply; note that
the chassis is designated A6, therefore reference designations for chassis-mounted compo-
nents other than major assemblies (A1-A5, A7-A14) are prefixed by A6.
FIGURE 4-5. MBT SERIES POWER SUPPLY, LOCATION OF MAJOR COMPONENTS