American Magnetics 430, Инструкции по установке, эксплуатации и обслуживанию

Страница: 205 / 254

R
EV
9 189
A
MERICAN
M
AGNETICS
, I
NC
. S
ERVICE
: T
ROUBLESHOOTING
H
INTS
continuity between the persistent switch heater power supply output pins at
the rear panel
MAGNET STATION CONNECTORS
and the connectors
on the magnet support stand top plate. Refer to page 194.
T
HE
S
YSTEM
C
URRENT
R
AMPS
S
LOWLY FROM
Z
ERO
With the Model 601 Energy Absorber in the system, an initial charging
delay will be observed when operating without an inductive load (e.g. a
persistent switch is not heated on a connected magnet).
1. To decrease the amount of time delay, increase the ramp rate to 1 A/sec or
greater value. Remember to decrease the ramp rate, if necessary, before
heating the persistent switch of the connected magnet and attempting to
ramp the current.
2. The charging delay will not be observed when operating with an inductive
load.
T
HE
M
ODEL
601 F
AULT
L
ED
E
NERGIZED WITH
A
UDIBLE
A
LARM
1. Verify that the supplied external DC power converter is connected to the rear
of the Model 601, and the AC power cord is also connected to the appropri-
ate power receptacle.
2. If the DC power converter is connected properly, observe if an internal green
LED is energized by looking through the Model 601 rear-panel grating. If the
green LED is energized, then the DC power converter is operating correctly.
If the internal green LED is not energized, then the DC power converter has
failed, or AC power to the DC power converter has been lost. Contact an
Authorized AMI Technical Support Representative for a replacement.
3. If the DC power converter is connected and the internal green LED is ener-
gized, then the FAULT LED indicates the failure of an internal energy absorb-
ing element. Do not continue to operate the unit and contact an Authorized
AMI Technical Support Representative for further instructions.
T
HERE IS
E
XCESSIVE
LH
E
B
OIL
-
OFF
D
URING
O
PERATION
Excessive LHe consumption is usually attributable to one or both of the
following: thermal energy being conducted into the cryostat or electrical energy
being converted into thermal energy within the cryostat. Analyzing the
circumstances under which the high boil-off occurs will help determine what is
causing the problem.
1. For magnets equipped with switches for persistent operation, verify that the
persistent switch heater power supply is operating at the proper current for
the installed switch. Excessive currents cause excessive boiloffs. The typical
switch requires approximately 45 mA to function correctly. Refer to the docu-
mentation provided with the magnet for proper operating current. See
page 108.
2. Verify that the protective diodes on the magnet are not turning on. Damaged
diodes may short causing current to flow through them whenever magnet
current flows and cause excessive heating. This can be identified by observ-