Edwards SCU-350 Series

SCU-350 Series Control Unit for Turbomolecular Pump
MT-21E-201-E
Page 76
6
MAINTENANCE
Table 25 shows the status of LCD, LEDs, and REMOTE output signals at a power failure.
Rotational speed
Duration of power
failure
LCD LEDs
REMOTE output signal
(I/O TB1)
Error
messages
Backlight
POWER
LED
FAILURE
LED
POWER
ALARM
N.O. N.C.
Backup rotational
speed or more
Approx. 2 sec. or
more
POWER
FAILURE
Extinguish
less than
20,000
rpm
Extinguish Illuminate Open Close Open
Less than approx.
2 sec.
Continues as before
Less than backup
rotational speed
OFF Extinguish Extinguish Extinguish Open Open Close
Table 25 - States of LCD, LEDs and REMOTE output signals at a power failure
6.1.2 Operation after a power recovery
1. The STP pump continues decelerating, and power failure detection is reset automatically.
At this time, the "POWER" LED illuminates and the "FAILURE" LED extinguishes. Also, POWER
OUT terminals (7)-(8) is closed, and a failure signal is reset between ALARM OUT terminals
(10)-(9) and (10)-(11) of the "I/O TB1" terminal.
2. When the START operation is performed after a power recovery, the STP pump reaccelerates
even while it is in BRAKE state.
However, the SCU-350 may detect excessive vibration when power is recovered after the rotor
lands on the touch down bearing. In this case, the STP pump once stops and cannot
reaccelerate until the RESET operation completed (see Section 4.4.4, "Starting the STP Pump
after a safety function operates", Section 4.5.8, " Starting the STP pump after a safety function
operates (I/O TB2)", Section 4.5.11, " Starting the STP pump after a safety function operates
(CON4)").
Note: It is recommended to establish a procedure so that the power can be supplied to the SCU-350
immediately after a power recovery.