Symptoms

Intermittent fault, presenting like a blocked chamber after a short period of operation. There will be sounds of the relief valve opening for an extended period of time, before the PLC timeout is reached and the intensifier shuts down. After a cooling down period, the instrument will be able to restart the intensifier and cycle normally until this problem reoccurs.


Diagnosis

First steps can be performed by any competent user, later steps should only be performed by Analytik engineers, or a confident power user at the customer site.


Users can eliminate:

  • Blocked chamber
  • Loss of prime
  • Failed/trapped plunger seal
  • Low oil
  • High oil

Analytik engineer or confident power user:

  • Open control box and remove the top cover from the M110P case.
  • Run cycle instrument and observe:
    1. Position sensors - Do they both have the green LED on? Does the amber light come on for each sensor when the cylinder reaches the respective positions for each sensor?
    2. PLC - 
      • I1.0 and I1.1 correspond to the extend and retract sensors (usually retract is I1.0, but some times the instruments sensors and DCV are wired "backwards") 
      • The retract sensor LED should be lit while pressure is being built up for an extend stroke, and the extend sensor should flash briefly when the the plunger reaches full extension.
      • The LEDs on line 00 at the top of the PLC - 00.1 and 00.2 should be illuminated while pressure is building. 00.1 should deactivate and 00.0 should briefly activate when the signal for an extend stroke is sent to the DCV.
      • Are the correct signal voltages being sent and received in the control box?

Root Cause Identification:

  • Sensors: If the green LEDs on the sensors do not activate, or the amber lights do not activate when the cyclinder is in the relevant positions, then there is likely to be a fault with one or both of the sensors. The minimum repair is to replace the sensor exhibiting faulty behaviour, but as both sensors are located in more or less the same place in the hydraulic system, both are likely to have experienced similar stresses, and if the fault was caused by damage from overheated oil, then both sensors are likely to be damaged to some extent.
    • Replace one, ideally both, sensors
  • PLC: If the sensors are behaving correctly and the signals are being received at the PLC, but not sent to the DCV, then there is a problem somewhere in the PLC circuit. This may require replacement wiring, relays, or re-formatting the PLC. 
    • Contact MF for further instructions
  • DVC: If the signals are being received and sent at the PLC as normal, then there is likely to be a fault with the DCV. This is the least likely root cause.
    • Contact MF for further instructions; likely to require replacement DCV.