Steam Turbine Pressure Switch ST307-350-B: The Absolute Barrier for Pressure Protection

When that steam turbine is cranking, the control pressure in the EH oil system and the lube oil supply pressure all need constant monitoring via pressure switches. The ST307-350-B pressure switch is a core defense part. Once you set the threshold, it has to be perfect—never trip early, and trip instantly when the pressure hits the number. How does it manage this? It starts by being built tough enough for the awful environment around the turbine.

I. Built Strong: Creating a Solid Platform

Turbine oil mist and heavy vibration are the switch’s hidden enemies. The ST307-350-B pressure switch’s housing is integrated cast aluminum, meaning no seams or gaps for oil mist to sneak through. Inside, the casing is lined with damping rubber. When the turbine’s vibration travels to the switch, that rubber absorbs the shock, stopping the internal parts from shaking loose or moving.

The wiring compartment seal is even more detailed. The cover uses an oil-resistant silicone rubber ring that gets pressed down tightly against the casing. The cable entry uses a metal waterproof joint where an internal rubber ring clamps down tight on the wires. This design keeps the internal circuits dry and clean, even inside a foggy EH oil station, so oil contamination never causes bad contact.

II. Sensing Core: Keeping the Pressure Signal Honest

The switch’s accuracy is all about the pressure sensor itself. Pressure switch ST307-350-B uses a metal diaphragm sensing structure made of Hastelloy alloy. This material has uniform thickness and super stable elasticity—when pressure changes, the diaphragm bends in a perfectly straight line relative to the pressure. It won’t get tired or lose its springiness over years of use.

The trigger assembly underneath the diaphragm is stainless steel. The push rod connects to the contacts using a rigid snap-fit design—no play, no gaps. When pressure reaches the set point, the diaphragm shoves the rod, and the contacts close in a blink, with no fuzzy “half-connected” state. This design kills the delay caused by pressure drift right at the source. For example, when lube oil pressure drops to the 0.15 MPa safety threshold, the switch fires in less than 10 milliseconds.

If your turbine pressure switch is slow to act, it’s highly likely the sensor element is worn out. Get in touch with us to check if you need a compatible ST307-350-B replacement.

III. Anti-Noise & Calibration: Guaranteeing Accuracy Long-Term

Motors and VFDs nearby the unit often generate EMI that can mess with the switch’s electrical signal. The ST307-350-B pressure switch’s internal circuit has a built-in electromagnetic shielding layer. This shield is wired directly to the grounding terminal, pushing the interference into the ground so it doesn’t affect the contact logic.

Routine maintenance calibration is simple. The face has an adjustment knob. Apply the target pressure with a standard pressure calibrator and turn the knob to set the threshold. On your monthly patrol, just use a multimeter to check the contact status against the pressure value to confirm accuracy. This easy calibration process means staff can keep the switch working perfectly without having to dismantle it.

Conclusion: The Right Switch is Key to Reliable Protection

The precision and stability of the ST307-350-B Pressure Switch are the result of combining tough structure, a high-quality sensing core, and smart anti-interference design. Its reliable performance in the EH oil and lube oil systems creates a “pressure safety net” for the turbine, avoiding the massive costs that come from false trips or failures to trip when needed.

If you need to replace your turbine pressure switch with something accurate and reliable, or if your existing ST307-350-B needs calibration, call us. We supply genuine, original switches and offer on-site adjustment services with the right calibration tools. We make sure your turbine hydraulic system pressure protection is always exactly right, so you can run worry-free.

E-mail: sales@yoyik.com
Tel: +86-838-2226655
Whatsapp: +86-13618105229

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