A turbo molecular pump controller does three electrical jobs. It supplies power, it drives the pump's motor, and it controls and reports on the pump. Pfeiffer's manual for its TC 400 controller sums up the last two: the unit is there "to drive, monitor and control the entire turbopump." So an electrical fault lives in one of three places: the power supply, the motor drive circuit, or the control and communication circuits. Here is what each part does, how its failure shows, and what to check before you send anything.
The power supply
The supply turns mains power into the DC the drive runs on. Pfeiffer's turbopumps take 24, 48 or 72 V DC, from an external supply pack or one built into the pump's electronics.
When the supply fails, the signs are blunt: nothing lights up, or the controller reports a voltage fault. The TC 400 has an error code for excess voltage and a warning for undervoltage or power failure, and its manual names the wrong supply pack or mains voltage as causes.
The motor drive circuit
The drive circuit spins the rotor. Pfeiffer's turbopumps use brushless DC motors that turn at up to 1,500 Hz, or 90,000 rpm.
When the drive fails, the pump will not spin up, or it starts and never reaches full speed. The TC 400 reports a drive fault, with a defective device as its cause. It also reports heat: excess temperature in the electronics, the motor or the final stage, with insufficient cooling given as a cause.
Control and communication
The control circuits:
- run the start and stop logic
- read the rotor speed and temperatures
- light the display or LEDs
- talk to the tool through a remote connector or a serial port such as RS-485
When they fail, the controller may refuse to start, lose track of the pump, or run while the tool cannot see it. The TC 400 has codes for an internal communication error, a faulty speed measurement, and a drive unit that does not detect its turbopump.
Rule out the rest first
An alarm on the controller does not always mean a bad controller. Pfeiffer lists leaks, open valves and a run-up time set too low among the causes of a run-up error. Its HiPace 400 manual adds two more: a defective bearing that drags on the rotor, and poor ventilation. Before you ship anything, work through our guide, Troubleshooting turbo pumps, which covers the code, the power, the cables and the cooling.
If the alarm survives those checks, the controller is the likely culprit.