Advanced Energy MDX II User Manual page 74

®
Advanced Energy
target when new
target at end of target life (EOTL)
To calculate the operating currents, use
current for new target
current at EOTL
Now you have the voltage range and current range for the target over its useful life. The
voltage and current values for the target when it is new and then at EOTL have been plotted on
Figure 5-3 on page 5-13. Notice that the EOTL current, 25.1 A, is out of the range of tap 4.
You can go a step farther and calculate the impedance for the target at both stages by using the
Target Impedance
calculate
impedance for new target
impedance at EOTL
The impedances are plotted on Figure 5-4 on page 5-14; you can see that the EOTL impedance
is out of the range of tap 4. The MDXII unit's front panel would indicate that the displayed
setpoint value is not equal to the actual output value. An "Out-Of-Setpoint" (page 8-9) or an
'Incorrect Tap Selected" (page 8-7) message may appear on the display.
One option for addressing this problem is to change the tap when the maximum current for the
tap is reached. Another option is to reduce the power level until the actual output level is equal
to the setpoint.
A third possibility is to use an MDXII unit model that produces more power. The two
impedances are plotted on Figure 5-5 on page 5-15, which shows the impedance boundaries
for the six taps available on the MDXII 30K unit; you can see that both fit within the tap 4
boundaries.
5-10
780 V
550 V
Current
=
13.8kW
------------------
=
780V
13.8kW
------------------
=
550V
Target Voltage
----------------------------------- -
=
Target Current
780V
------------- - 44Ω
=
17.7A
550V
------------- - 22Ω
=
25.1A
Operation Overview
Power
--------------------
Voltage
17.7A
25.1A
5700262-R