CPI CMP 200 Series Service Manual page 284

CPI Canada Inc.
7.2.2 DC bus & power distribution (MD-0927)
Sheet 1 applies to single-phase generators:
Assuming that the AC mains is connected and switched on, line voltage is applied to the primary of the
auxiliary transformer via F8 and F9 on the H.V auxiliary board. This will establish the +/-35 V supplies via
F1 and D1, and the +24 V supply via F2 and F3, and D3 / D4.
When the generator is switched on as described in 7.2.1, +24 V is supplied to the consoles via K1 and F2
on the generator control board. For the membrane console, the +24 V supply is regulated to +5 V and -20
V on the console board (page 4). The touchscreen console is powered from the +24 V supply; on-board
regulators step this down as required by the internal circuits. The low voltage DC supplies on the
generator control board are also established when the generator is switched on, as per 7.2.1.
K2 on the H.V. auxiliary board will be energized when the soft-start command is received from the CPU.
This will pre-charge the DC bus capacitors via F4 and F5, K2, D5 and series current limiting resistors. The
DC bus charging current flows through R17, developing sufficient voltage drop to energize U5. At the start
of DC bus capacitor charging, current through R17 is at its maximum. U5 will be on at all times except
near the zero crossing of the AC current waveform. The output of U5 will as per figure 1 on page 5 of MD-
0927 (early charging). As the bus capacitors approach a fully charged state, the current in R17 will
approach zero. U5 will only be on near the peaks of the AC current waveform, and the output of U5 will as
per "nearly finished charging" in figure 1 on page 5 of MD-0927. When the CPU detects the "nearly
finished charging" state via U5, the main power contactor and the cooling fan will be energized. The line
voltage is then rectified by the chassis-mounted mains rectifier assembly to produce approximately 320
VDC for 230 VAC input. This DC bus voltage is switched by the inverter board to produce the drive for the
primary of the HT transformer as described in 7.2.5.
LED DS1 on the H.V. auxiliary board confirms the presence of the +24 VDC supply, and DS1 on the EMC
capacitor board indicates that the DC bus is charged.
The BUCKY DRIVE output may be configured for +24 VDC, 110 VAC, or 220 VAC. Connecting E11 to E5
and E7 to E8 supplies +24 VDC, wiring E9 to E5 and E7 to E8 supplies 110 VAC, and jumpering E12 to
E5 and E7 to E8 outputs 220 VAC.
K6 on the H.V. auxiliary board will be energized when the +12 V supply on the generator control board is
present, supplying +24 VDC, 120 VAC, or 240 VAC to the Bucky drive circuits (section 7.2.3).
The low-speed starter boost voltage is jumper selectable to be 120 or 240 VAC. Connecting E16 to E15
selects 240 V boost, and jumpering E14 to E15 selects 120 V boost.
As described in 7.2.1, the +5 V, +12 V, and +15 V switching regulators become operational when the
generator is switched on. The –12 V, +1.2 V, and +3.3 V supplies are derived from the +12 V and +5 V
supplies, respectively.
Sheet 2 applies to three phase 208 / 230 V generators:
With respect to MD-0927, the operation of three phase 208 / 230 V generators is similar to that described
above for single-phase generators.
Sheet 3 applies to three phase 400 / 480 V generators:
With respect to MD-0927, the operation of three phase 400 / 480 V generators is similar to that described
for single-phase generators.
The rectified DC bus voltage for 400 VAC units will be approximately 560 VDC, or approximately 670
VDC for 480 VAC units.
Use and disclosure is subject to the restrictions on the title page of this CPI document.
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CMP 200 X-Ray Generator Service Manual Ch # 901476-09 Rev. C
7
Theory of Operation
Page 7-3