Figure 5.2 Output Current Measurement
A series terminating resistor (or series inductor or clamp diode) must be added as shown if
the average value of the peak current exceeds 110% of the normal output current.
When choosing Rs, ensure it can withstand the full output voltage across it as well as the
power dissipation caused by discharging Co (see Table 5.1) and Cc (20pF/ft) (65.62 pf/m)
each cycle as well as conducting the normal output current. It's power dissipation can be
calculated as
.
Pd
= (
I
O
2
R
S
) +
1/2
(
C
O
+
C
C
)
V
2
(
REP RATE
)
Table 5.1 Output Capacitance
230pF
40kV
460pF
10-30kV
15nF
3kV-6kV
60nF
1-2.8kV
Co
Output Voltage
The 500A/102A/152A/202A power supplies are designed for simple parallel operation. The
input power and HV output should be connected directly together. The REMOTE
connectors on the input panel can also be connected directly together using a "daisy chain"
ribbon cable from the system controller. Each of the power supplies operate at the same
time with the total charge rate equal to the sum of each.
Sometimes when operating several units in parallel, the high total power generates noise
which interferes with the power supply control. This is usually due to the many
interconnecting control cables acting as an antenna picking up noise. The problem usually
appears as one or more of the power supplies shuts down when the output voltage increases
beyond a certain level. Dressing the control cables as short as possible and close to ground
or using shielded cables should help. In severe cases, it is necessary to wrap the cables
several times through high permeability ferrite cores at the input panel of each unit.
The 500A/102A/152A/202A power supplies can also be used as an Isolated High Voltage
continuous DC power source by adding an external filter capacitor. The value of the filter
capacitor depends upon the value of the allowable output voltage ripple value. For parallel
operation into DC loads, please contact EMI Customer Service Department. (See Section 5.6).
83-493-001 Revision G
5 - 2
Applications
