The choice of PVE also decides the level of feedback and safety. PVE are available with fault monitoring,
spool direction indication, spool position feedback and separate float control.
The fault monitoring is available in PVEA/H/S/P/U and is a utilization of the ASIC.
Direction Indication is available in PVEO/A/H and they are dual powered PVE where separate pins give an
active feedback for spool movement.
Spool position is available in PVES and is a precise feedback on a separate pin for actual spool position.
The separate float control is a protection against unintended float activation.
The PVEM, PVEO and PVHC do not have fault monitoring.
Fault monitoring and reaction
The fault monitoring system is available in two versions:
•
Active fault monitoring provides a warning signal and deactivates the solenoid valves. A reboot of the
PVE is required to reactivate.
•
Passive fault monitoring provides a warning signal only. A reboot is not required.
Both active and passive fault monitoring systems are triggered by the same four main events:
1. Control signal monitoring
The Control signal voltage (US) is continuously monitored. The permissible range is between 15% and
85% of the supply voltage. Outside this range the section will switch into an error state. A
disconnected US pin (floating) is recognized as neutral set point.
2. Transducer supervision
The internal LVDT wires are monitored. If the signals are interrupted or short-circuited, the PVE will
switch into an error state.
3. Supervision of spool position
The actual position must always correspond to the demanded position (U
S
). If the actual spool
position is further out from neutral than the demanded spool position (>12%, PVEA: >25%) or in
opposite direction, the PVE will switch into an error state. With neutral/blocked setpoint the tolerance
is +- 0,5 mm relative the calibrated neutral position. Spool position closer to neutral and in same
direction will not cause an error state. The situation is considered “in control”.
4. Float monitoring
Float must be entered or left within a time limit. On the six pin float PVE too high delay will cause an
error state. The float Time Outs has own thresholds. Only relevant for the six pin PVEH-F.
Active fault reaction is activated after 500 ms of error (PVEA: 750 ms).
•
The solenoid valve bridge is disabled and the PVBS is released to spring control
•
The error pin is powered*
•
The LED change color
•
The state is memorized and continues until PVE reboot
Passive fault reaction is activated after 250 ms of error (PVEA: 750 ms)
•
The solenoid valve bridge is NOT disabled and the PVBS is NOT released
•
The error pin is powered ( for PVE with direction indication both DI pins goes low by fault.)
•
The LED change color
•
The state is active for minimum 100 ms and is reset when error disappears
Technical Information
PVE, Series 4 for PVG 32/100/120 and PVHC
Safety and monitoring
520L0553 • Rev GD • Jan 2014
15
Summary of Contents for PVE 4 Series
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