9. Calibration

9.1. Control Board

The control board contains digital potentiometers for fine adjustments of the reference and feedback amplifiers. These potentiometers may be adjusted by using the front panel controls described in Calibration. These potentiometers can also be adjusted by using the Calibration Panel of the Remote Interface Software.

9.1.1. Reference Amplifier Calibration

Connect a voltmeter between Pin 6 of JS1 37-pin external user I/O (positive) and Pin 1 of JS1 37-pin external user I/O (negative). With only the control power applied, adjust potentiometer P5 for a 2.5006 V.

9.1.2. Voltage Feedback Amplifier Calibration

Place a DC voltmeter across the output terminals of the power supply and place a second DC voltmeter to monitor VO2, the voltage between Pin 5 of JS1 37-pin external user I/O (positive) and Pin 1 of JS1 37-pin external user I/O (negative). Set the load to 50% rated output current at full scale voltage.

With only the control power applied, adjust potentiometer P2 for 0.000 V at VO2. Using the up/down (V/I DIS or TRIP DIS) keys or RS232 remote interface, set the output voltage to 50% full scale output. Turn on the power supply and adjust potentiometer P1 until the output voltage matches the set point voltage. Now set the output voltage to its full scale rating and measure the output voltage. Adjust potentiometer P1 to equally divide the error between the half scale set point and the full scale point.

9.1.3. Current Feedback Amplifier Calibration

Place a DC ammeter in series with the load of the power supply and place a DC voltmeter to monitor IO2, the voltage between Pin 24 of JS1 37-pin external user I/O (positive) and Pin 1 of JS1 37-pin external user I/O (negative). Set the load to 100% rated output current at 90% full scale voltage.

With only the control power applied, adjust potentiometer P4 for 0.000 V at IO2. Using the up/down (V/I DIS or TRIP DIS) keys or RS232 remote interface, set the output current to 50% full scale output. Turn on the power supply and adjust potentiometer P3 until the output current matches the set point current. Now set the output current to its full scale rating and measure the output current. Adjust potentiometer P3 to equally divide the error between the half scale set point and the full scale point.

9.2. Driver Board

The driver board contains two potentiometers which are used to set under voltage and over current protection in the polyphase chopper circuitry. These potentiometer do not normally need adjustment in the field.

9.2.1. Over Current Protection

Over current protection should only be calibrated after consultation with the factory.

Caution

Gross misadjustment of the over current protection can cause chopper and inverter failure.

Place a DC voltmeter between test point TP6 (positive) and test point TP7 (negative) on the driver board. With only the control power applied, adjust potentiometer P1 to 6.00 V.

9.2.2. Under Voltage Protection

Under voltage protection should only be calibrated after consultation with the factory.

Caution

Gross misadjustment of the under voltage protection can cause chopper and inverter failure.

Connect the power supply to an adjustable AC source and connect an AC voltmeter to monitor the voltage applied to the input terminals. Tests can be performed under no load conditions. Set the AC source to the power supply’s rated input voltage. Turn the control power, press the start switch, and adjust the output voltage to 10% full scale output. Decrease the AC source to a value between 75% to 82% of rated voltage. Adjust potentiometer P2 until the output drops to zero; the transition will be abrupt.

Decrease the AC source to a value between 72% to 79% of rated voltage. The main contactor should turn off.