American Magnetics AMI Superconducting Magnets - Manual (Page 20)

19
3 Troubleshooting
The following troubleshooting aids are included to assist he user in identifying and
correcting magnet system problems. In the event that the trouble cannot be corrected,
please contact an AMI representative for assistance.
Magnet not charging
1. Voltage indicated on power supply; No voltage developed across magnet.
a. Make sure the programmer/ power supply system has been setup and
tested in accordance with the respective manuals. Specifically the
installation section of this manual which entails operating the power
supply system
b. Check all connections for proper contact and connection. Voltage present
with no current flow is indicative of an open circuit.
c. Make sure the power supply current leads are securely connected to the
vapor-cooled current leads with no ice or debris between the contact
points.
d. If using an polarity switching energy absorber in the power supply
system, make sure the energy absorber is properly energized.
e. If the current ramps up and no voltage developed across magnet, make
sure the persistent switch heater is properly energized and the proper
amount of current is flowing through the persistent heater. The persistent
switch heater current specification and the magnet inductance
specifications are recorded on the Magnet Specification Sheet. The
voltage across the magnet is governed by the equation E = L * (dI/dt).
Make sure the proper current is flowing to the persistent switch and the
proper connections are made. If the problem continues, investigate a short
circuit across the magnet.
f. If voltage is present at the magnet leads but minimal current flows, the
magnet may not be at 4.2K. Make sure the liquid helium level is above the
magnet and the helium boil-off has stabilized at the expected level. Also,
physical damage to the magnet wires may cause these symptoms. If this
magnet damage is a possibility, call AMI and speak with a sales
representative.
2. No voltage indicated on power supply; No voltage developed across magnet.
a. Make sure the programmer/ power supply system has been setup and
tested in accordance with the respective manuals.