A hydraulic power pack for structural testing isn't just plumbing — the control system determines test validity, equipment longevity, and operator safety. Here's the architecture.
Pressure Control Loop
The PLC regulates system pressure to a 210 bar setpoint using a PID loop on the proportional pressure relief valve: a fast proportional term, an integral term (clamped to ±20 to prevent windup), and a small derivative term for damping, with the combined output clamped to the valve's 0–100% command range. This keeps pressure tracking tight under the load swings a structural test rig actually produces.
Temperature Management
Hydraulic fluid temperature is managed across three bands. Below setpoint by more than 10°C, a heater assists cold-start warming; within the modulating range, the cooler bypass valve holds around 50% to keep temperature steady; above setpoint by more than 5°C, cooling ramps in proportionally. At 65°C the system forces full cooling and raises an alarm, and at 75°C it executes an emergency shutdown — protecting both fluid viscosity-dependent test accuracy and the pump/seal hardware from heat damage.
Safety Interlock Sequence
Per EN 13849 PLc, the system checks six startup permissives before allowing the pack to run: reservoir level above 40%, fluid temperature between 20–65°C, filter differential pressure below 5.0 bar, all guard switches closed, E-stop not pressed, and fluid cleanliness at NAS class 6 or better. All six must be true to start. Once running, five independent runtime triggers — over-temperature, low fluid level, filter bypass, system pressure above 230 bar (10% over rated), and motor overcurrent above 115% FLA — will shut the pack down immediately if tripped.
Neometrix HPP 230/210 implements this control architecture with PLC-based pressure regulation, temperature management, and EN 13849-compliant safety interlocks.
→ https://neometrixgroup.com/products/hydraulic-power-pack-230-lpm-210-bar
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