Delta HES Series Instructions For Use Manual page 49

Troubleshooting for Pressure Instability
Unstable pressure over the entire section
1. Set Pr. 00-09 = 0 for speed control
2. With the oil line in the closed state, send the low speed rotation command to make the
pressure feedback 40~50% of the pressure command value (Pr. 00-07)
3. Check if the pressure waveform shows any jitters through the monitoring software.
Jitter in Pressure Waveform

The possible cause is interference from ground. If the motor or the three-phase
power supply is grounded, disconnect the ground wire. If the motor or the
three-phase power supply is not grounded, add the ground wire for interference
protection.
The other possibility is the ground issue of the shielding mesh (as illustrated by
the bold red lines in the figure below). If the shielding mesh is grounded,
disconnect the ground wire. If the shielding mesh is not grounded, add the ground
wire for interference protection.
PG Card
14,16
13,15
+24V
ACM
PO
4. Please contact the original manufacturer if the anomaly still cannot be resolved after
resorting to the methods described above.
Step 8. Adjustment of System Transient Response
Reduce the pressure ramp up time by increasing Kp1 (Pr. 00-20) and reducing Ki1 (Pr.

00-21) times
When the pressure is over-adjusted, increase Kp3 (Pr. 00-24) and reduce Ki3 (Pr. 00-25)

times
5
4
7
9
3-11
Chapter 3 Flow of machine AdjustmentHES Series
Resolver
R1
R2
S2
S4
S1
S3
+V
-V
O u tp u t
te rmi n a l