Transformer Tapping - Siemens SINUMERIK 840D Maintenance Manual

3.2 TRANSFORMER
TAPPING
OCTOBER 2005
1. With the machine main power switch turned OFF, verify that the chart on the door of
the cabinet is the one for the transformer in the machine.
2. Measure the input voltage to the machine on the chart (Measure leg to leg the input
power lines to the machine.).
3. Next to the voltage on the chart will be a "jumper" number, such as 3-6, and a "AC
Input" number, such as 7.
4. Each phase has a group of terminals such as A3 to A8 for phase 1 and B3 to B8 for
phase 2. Place a jumper between the two terminals listed on the chart for each
phase. Using the same example place jumper from A3 to A6 for phase 1, B3 to B6
for phase 2 and one from C3 to C6 for phase 3.
5. Place the input tap wire in the proper terminal, as in example A7 for phase 1, B7 for
phase 2 and C7 for phase 3.
The VMC is Ready for the Initial Power on Procedure
6. Push the EMERGENCY STOP switch to disable the axes.
7. Turn ON the main power switch.
8. Measure the voltage at the transformers secondary between A12-B12, A12-C12,
B12-C12.
9. Measure the out voltage of transformer, labeled A12, B12, C12, leg to leg. Should
be about 230 VAC with the range being from 220 to 240 VAC. If the difference
between 230 and the measured voltage is greater then ten (10) volts then power
down. If the voltage is too high then select the next higher voltage on the chart and
change the jumper and / or input tap and recheck. If the voltage is too low then
select the next lower voltage and change and check.
10. Check the voltages on the D.C. power supply, i.e. 5, + 12, -12 VDC, +24VDC.
11. Push the CNC POWER button.
12. Reset the EMERGENCY STOP switch.
13. Unbolt and remove the support between the table and the head.
14. Unbolt and remove the counterweight bars from the column, located next to the
main disconnect box.
15. Jog the axis to the cold start indicators and cold start the VMC.
NOTE
It is acceptable to have the legs tapped differently by one voltage tap position. There should be no
more than one position.
INSTALLATION PROCEDURE
SIEMENS MAINTENANCE MANUAL
49