American Magnetics 420 Power Supply Programmer - Manual (Page 116)

98 Rev. 7
Service
Troubleshooting Hints
Note
If the persistent switch heater is activated without an inductive load
present at the supply outputs, oscillating current will result. The
Model 420 is designed to operate large inductive loads with only
relatively small resistive characteristics (i.e. superconducting
magnets). The Model 420 is not designed for use as a general
purpose power supply controller for resistive loads.
3. If the magnet has no persistent switch installed, or has a small
inductance (typically less than 1 Henry), then adjust the stability
setting for the Model 420. As this setting is increased, the system
should become more stable. For best results, minimize the amount
that this value is adjusted from 0.0%. Refer to paragraph 3.2.2.1 on
page 44.
5.2.4 The power supply system will not charge the magnet.
1. Verify system interconnecting wiring. Refer to paragraph 2.5 on
page 15. If the Model 420 shows “+0.00 A
↑
Status: Ramping” with
the supply voltage, Vs, increasing or at the programmed voltage
limit (as indicated by the
92/7$*( /,0,7 LED), there may be a
problem with the power supply. Verify the power supply is on and
the program out connection from the Model 420 to the program
voltage input to the power supply is intact.
2. Verify the power supply is configured for remote programming,
voltage-to-voltage mode. Consult the manufacturer’s operations
manual for the necessary power supply configuration.
3. Ensure the Model 610/630 Energy Absorber / Reversing Switch
control unit is energized. By default, lack of power at the Model
610/630 causes a contact to shut which crowbars the power supply
downstream of the Model 420 shunt.
5.2.5 The Model 420 will not charge the magnet at the selected
5$03 5$7( .
1. Ensure the Model 420 is properly configured for the connected
power supply. See paragraph 3.2.1 on page 40.
2. Ensure that the persistent switch heater is on and the switch
heating time has expired. Ramping is disabled during the switch
heating period.
3. With the persistent switch heater on, press the 1 key in the default
display to show the switch heater voltage. A value of 0 V indicates a
shorted switch heater connection. A value exceeding 17 V indicates
an open switch heater connection. The displayed voltage divided by