Technical information

155
Troubleshooting
(a) Single point ground should be used for chassis, power supplies, etc., with each
having an individual ground wire of the appropriate size (gauge). Single point
ground must be proper earth ground.
(b) All coils in system should be properly suppressed, AC coils and relays with RC
networks, and DC coils and relays with diodes (see the Installation chapter).
(c) Power supply used for I/O must be 10.5 to 30 VDC. DC common must be
grounded to the single point earth ground.
(d) Check for any EMI/RFI sources on the same AC circuit or in close proximity to
the drive (i.e., high power induction drives or welding machines).
(e) Check the serial interface connection.
(f) If high and low power wires are in close proximity, they should cross at 90°
angles.
(g) Check for static discharge.
13. Stabilization of high inertial loads.
(a) Using default gain parameters, the FX drive’s compensation control range is
adequate to provide stable operation of loads whose inertias are up to ten times
greater than the motor. Instability due to large inertial mismatches will cause the
system to oscillate while stopped or to “lope” at higher RPM’s. The term
“loping” is used to describe a low frequency change in velocity. If either of
these conditions are noticed, changing the system gain parameters may help.
For inertial mismatches (load to motor) greater than 10, the following procedure
may help stabilize the system.
(i) The gain parameters that can be varied are “EG” (position loop gain) and “GS”
(gain scale). These parameters can be adjusted using the “Terminal Mode” menu
choice in PCX. The ASCII serial commands used to change the values are EG=XX
and/or GS=XX; where XX= the desired HEX value.
(ii) For this stabilization procedure the value of EG should be decreased while the
value of GS is increased. If increasing the value of GS causes a high frequency
oscillation, it should be lowered to an acceptable level.