Danaher Motion
05/2008
Appendix E – Voltage Sag Standard – Semi F47, F42
S200-VTS Product Manual
125
APPENDIX E – VOLTAGE SAG STANDARD – SEMI F47, F42
Semiconductor F47 and F42 standards relate to the ability of equipment to
ride-through
voltage
dips of various magnitudes and duration. F47 requires that semiconductor equipment tolerate
transient voltage sags or dips on the AC power line. Voltage dip to:
50% of nominal for 200 ms
70% of nominal for 0.5 second
80% of nominal for one second
F42 specifies how to test for compliance with F47. To robust the S200 for F47 type voltage
sags, power the S200 using AC line voltage and phasing as
described below.
AC S200 Control Power
240 VAC, one-phase
AC S200 Bus Power
Three-Phase, 240 VAC
DC S200
DC power supply operated from three-phase, 240 AC line
AC Control Power
The use of 240 VAC, single-phase, nominal for control power results in the control voltage
remaining within the drive control voltage specification (85 VAC to 265 VAC) during an F47
50% sag (deepest F47-specified sag). Powering the control with 240 VAC also maximizes the
ride-through time for larger amplitude sags because more energy is stored in the control bus
capacitor.
AC Bus Power
If three-phase 240 VAC is available for bus power, it provides much better F47 ride-through
than either single-phase 240 VAC or 120 VAC because F47 and F42 standards mandate that in
a three-phase system, only one phase of the three phases is sagged at a time. If the AC S200
is powered by three-phase 240 VAC, it keeps its bus capacitors reasonably well-charged by
pulling power from the one line-to-line voltage that does not sag.
With single-phase AC bus power, a full torque acceleration of the motor to high speed during
an F47-mandated voltage sag has the potential to drag the bus voltage down. If only the
internal bus capacitors of a 3 A / 9 ARMS S200 are supplying the full 3 kW peak output power,
the bus voltage sag rate is 13 V/ms.
A single 10 to 20 ms motor acceleration during a 50% F47 voltage sag has the potential to drop
the bus voltage about 50%. Options to handle this problem are:
a) Limited hold-up time of 20 to 30 ms is achieved by adding additional capacitance on the
bus. Wire an external 1,500 uf or higher, 450 VDC, aluminum cap across the +bus to -bus. In
this case, simply wire a rectifier or surge limiter between the drive AC terminals and the cap to
help charge the external capacitance at power up. The bus voltage does not return to normal
until the line returns to normal, so multiple accelerations during the sag are a problem with this
option.
b) Monitor the line voltage and quickly
pause
the machine when the voltage sags.
c) Combination of a) and b)
d) A robust, costly option to ride through all F47 mandated voltage sags when three-phase
240 VAC is not available is either to double the peak power capability of the motor/drive
system, or to derate the motor's maximum speed 50%. If a motor’s top speed can be achieved
with a 50% low bus voltage, the worse case F47 voltage sag of 50% is tolerated with little or no
effect on motor performance.
If three-phase power is available within the plant, but at higher voltage than 240 VAC, consider
adding a power transformer to step it down to 240 VAC for use as AC bus power for the S200
drives in the machine. This is also a robust option.