Lake Shore 625, User Manual

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Lake Shore Model 625 Superconducting MPS User’s Manual
7-4 Service
The error messages are divided into two groups. Instrument hardware errors are related to the instruments internal
circuits. When one of these errors occurs, the output crowbar SCR will be thrown, the Fault LED will be lit and there
will be no way to clear the error unless power is cycled. If one of these error messages persist after power is cycled, the
instrument requires repair. Instrument hardware errors are listed in Table 7-1. Operational errors are related to instrument
operation and do not necessarily indicate a hardware problem. When one of theses errors occurs, the Fault LED will be
blinking and the error condition can be cleared once the fault condition has been removed. Operational errors are listed in
Table 7-2.
Table 7-1. Instrument Hardware Errors
DAC Processor not
Responding The processor that controls the output DAC is not responding or is responding
incorrectly. The output crowbar SCR has been thrown to prevent damage to the
magnet or the supply.
Output Control Failure One of the internally monitored voltages is beyond an acceptable range on power
up. The output crowbar SCR has been thrown to prevent damage to the magnet or
the supply.
Output Voltage >
Compliance Setting The output voltage is greater than the compliance voltage setting indicating a
problem with the compliance voltage circuitry. The output crowbar SCR has been
thrown to prevent damage to the magnet or the supply.
Output Over Current The output current exceeded 62 amps. The output crowbar SCR has been thrown
to prevent damage to the magnet or the supply.
Low Line Voltage Detected The input line voltage is detected to be too low. The instrument may not be able to
attain the compliance voltage setting. The output crowbar SCR has been thrown to
maintain control of the magnet.
Internal Temperature Fault The internal temperature of the supply has exceeded 80 °C. The output crowbar
SCR has been thrown to prevent damage to the supply.
Table 7-2. Operational Errors
Magnet Discharging
Through Crowbar The magnet is currently discharging through the output crowbar SCR. This error
can be cleared when the magnet is completely discharged.
Magnet Quench Detected A magnet quench has been detected because the output current changed at a rate
greater than the current step limit. This error can be cleared when the magnet is
completely discharged.
Remote Inhibit Detected An external remote inhibit condition was triggered. The output current is set to
zero. This error can be cleared when the remote inhibit trigger is released.
Internal Temperature High The internal temperature of the supply has exceeded 75 °C. If the output current is
increasing, the output current ramp will stop. If the output current is decreasing,
the compliance voltage will be limited to 1 V. This error can be cleared when the
internal temperature drops below 70 °C.
High Line Voltage Detected The input line voltage is detected to be too high. This error can be cleared when
the input line voltage is within specified tolerances.
External Current Program
Error The instrument was not allowed to change to external or sum current
programming modes because the programming voltage is greater than 0.025 V.
This error can be cleared when the programming voltage is less than 0.025 V or
the instrument is changed to internal current programming mode.
Calibration Invalid The instrument has either not been calibrated or the calibration data has been
corrupted. The error can be cleared at any time and the instrument can still be used
but there is no guarantee that it is operating within specifications. The instrument
needs to be recalibrated to correct this error condition.
PSH Short Detected The persistent switch heater circuitry has detected a short and the heater has been
shut off. This error can be cleared at any time and will be checked again when the
heater is turned back on.
PSH Open Circuit Detected The persistent switch heater circuitry has detected an open circuit and the heater
has been shut off. This error can be cleared at any time and will be checked again
when the heater is turned back on.