4 PRINCIPLES OF OPERATION
4.1 GENERAL
This supply rectifies and filters the AC input voltages, then a 20kHz switching buck
regulator regulates the output DC. Also supplied is a 25kV ignition pulse and 800V boost
to start the lamp. The A100 PCB compares the output current to the input reference and
adjusts the duty cycle up or down to maintain regulation.
Figure 5 Duty Cycle Regulation
4.2 POWER FLOW (SCHEMATIC 01-475-005)
The 208/220 VAC 3 Phase or 208/220 VAC 1 Phase power is applied to TB1 then to CB1
and on to the line filter A300. From the line filter, the AC is rectified by CR4, (CR4a and
CR4b for 1 Phase), and is filtered by L1 and C1, (L1a, L1b, C1a, C1b and C1c for 1
Phase P/S). The resulting DC is then chopped by the buck converter A200 and again
filtered by L2 & C2. CR5 is a blocking diode, which allows the injection of a boost voltage
and T1 is the ignition transformer, which produces the 25kV start pulse.
4.3 SIGNAL FLOW (SCHEMATIC 01-000-225)
The 208 VAC is applied to T3 & T4, which reduces the voltage to 15 VAC, which is
rectified by CR45, CR49, CR47 and filtered by C33, C35 and C37. U12, U13 and U14
regulate the rectified DC to produce three independence DC voltages, which supply the
control circuit with operating potential.
The main PWM is U8 and its' output is via P4, Pins 4 & 5. The control amplifier (Pins 1 &
2) is connected to the shunt and provides for current regulation. The control amplifier
(Pins 4 & 5) is connected to the attenuated voltage output and provides for the maximum
unloaded voltage output.
Pin 9, the shutdown pin, is controlled by U7, which in turn is controlled from the protection
circuits U1, U3 and U4. U5A, U6, T2 & U10B isolate the control signal which is used to
unbalance the inputs to the PWM (Pins 1 & 2).
The shunt voltage is amplified by U10A and fed to the isolation circuits of U11, T1 and
U4B. This channel allows the output DC current to be monitored by an external monitor
isolated from the DC shunt.
Page 13 of 18
83-475-001 Rev. D
Summary of Contents for ESKI
Page 6: ...Figure 1 Loss Pass Filter Page 4 of 18 83 475 001 Rev D...
Page 8: ...3 OPERATING INSTRUCTIONS Figure 2 Front Panels Page 6 of 18 83 475 001 Rev D...
Page 11: ...Figure 3 1 Phase Front Panel Control Hookup Page 9 of 18 83 475 001 Rev D...
Page 14: ...Figure 4A 1 Phase External Control Hookup Page 12 of 18 83 475 001 Rev D...
