The PA4008 is a highly stable 4-quadrant power supply unit that is used to feed different magnets of the storage rings of BESSY II and the PTB Metrology Light Source in Berlin.

Based on a linear, air-cooled amplifier, the power supply generates output currents of ±8 A at output voltages of up to ±40 V.

The overall stability of the output current is better than 100 ppm. This includes peak to peak ripple and noise, as well as thermal and long-term drift.

Its linear nature makes it possible to use the power supply for applications requiring highly dynamic output currents, too. Up to 1000 Hz power bandwidth can be achieved via the additional modulation input. The modulation signal is summed to the current setpoint. Optionally, the current setpoint can be multiplied by the modulation signal.

Current setpoint, actual values, control and status signals are exchanged via a control interface. A slot is provided to accomodate the customer's proprietary control interface or a standard interface card. This allows for the integration of the unit into the control system of the facility. Precision monitoring outputs pinpoint the actual values on additional connetors on the front panel.

In case of sudden setpoint changes, the rate of change is restricted by means of an adjustable precision slew-rate limiter.

Two DCCTs are used to measure the output current for regulation and for monitoring independently. This allows the control system to detect even small deviations in the output current.

The unit is fully protected against overload, overtemperature and short circuit. Many operational parameters like internal supply voltages, internal temperatures, output fuse, load current oscillation, DCCT operation and external interlock inputs are monitored. In case of a malfunction the unit will shut down and the status is stored. For a quick overview, the complete status information is indicated on the frot panel.

The construction is based on a 19" housing, 3 units high.


Output Current -8 - +8 A
Output Voltage -40 - +40 V / -20 - +20 V (switch selectable)
Overall Stability < ±100 ppm (over ambient temperature range, including ripple, noise and 8 h drift)
Ripple + Noise < 50 ppmPP (load: 100 mH / 1.5 O)
Absolute Accuracy < ±5*10-3
Power Bandwidth (-3dB) DC – 1000 Hz (via modulation input, into a suitable load)
Slew-Rate 1.6 A/s (adjustable)
Common Mode Voltage -100 - +100 V
Mains Voltage 3x 400 VAC / ±10% / 47 - 63 Hz
Power Factor > 0.6
Ambient Temperature +10 - +30°C (operating)
Dimensions (w x h x d) 483 x 132.5 x 554.5 mm (19", 3 U)
Weight 36 kg