8 MAINTENANCE
The SCU-1601 is provided with safety functions for various abnormalities/errors. If an
abnormality/error is found when using the STP pump, check it and take measures in accordance with
the following procedures. If you cannot trace it or if the STP pump does not function normally after the
troubleshooting, fill in the necessary information in the "Return Declaration" and fax it to Service office.
8.1 Safety functions
8.1.1 Power failure
When the power voltage drops below 160 V due to a power failure or another fault, the normal
operation of the magnetic bearing is maintained at the high rotational speed using the regenerative
energy of the rotating rotor (backup operation during a power failure).
The lowest rotational speed to which the magnetic bearing can operate at a power failure is called a
backup rotational speed. The lowest backup rotational speeds vary according to the model of STP
pump used, refer to Table 32.
1. When the rotational speed is at backup rotational speed or more at a power failure:
The SCU-1601 detects any power failure of 2 seconds or more and the STP pump decelerates.
At this time, the "POWER" LED extinguishes and the "FAILURE" LED illuminates.
The LCD displays "Mains Failure". An alarm signal is output from X7 REMOTE pins (14)-(33) and
(15)-(33). When the rotational speed reaches the backup rotational speed, the rotor lands on the
touch down bearing and stops. The "FAILURE" LED extinguishes and the LCD is turned off.
The alarm signal output is reset.
The SCU-1601 does not detect a power failure of less than 2 seconds and the STP pump will
continue to rotate.
2. When the rotational speed is less than backup rotational speed at a power failure:
The SCU-1601 does not detect the power failure. The rotor lands on the touch down bearing and
stops.
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