Yokogawa STD4A-00 S1 Pressure Clamp Terminal Block

The Yokogawa STD4A-00 S1 Pneumatic-to-Electric (P/E) Transducer, when specified with the Pressure Clamp Terminal Block, represents the high-reliability interface version of this classic signal conditioner. This terminal style is preferred in industrial environments to ensure secure, vibration-resistant electrical connections for the 4-20 mA output signals.

Technical Specifications

The S1 Suffix & Terminal Design

In this specific configuration, the S1 suffix confirms the hardware variant that utilizes Pressure Clamp Terminal Blocks. Unlike standard screw terminals where the screw spins directly against the wire, the pressure clamp uses a metal plate to compress the wire against the conductor.

• Security: Prevents "cold flow" or wire loosening over time.

• Wire Protection: Ideal for fine-stranded wires, as the clamp prevents the screw from cutting through individual strands.

• Efficiency: Faster to wire than ring-lug style terminals.

Installation & Wiring Guidelines

• Pneumatic Port: Connect the 3-15 psi line to the input port. Use a backup wrench when tightening fittings to avoid putting torque on the internal transducer bellows.

• Wiring the Clamp: 1. Strip approximately 7-10 mm of insulation.

  2. Insert the wire into the square opening of the clamp.

  3. Tighten the screw to the manufacturer-specified torque (typically 0.5 to 0.6 N·m).

• Vibration Resistance: The pressure clamp design is specifically rated for high-vibration areas (e.g., near compressors or large pumps) where standard terminal screws might vibrate loose.

Frequently Asked Questions (FAQs)

Does the STD4A-00 S1 require ferrules?

While the pressure clamp design allows for bare stranded wire, the use of insulated ferrules is highly recommended for safety and to prevent stray strands from causing short circuits between the closely spaced terminals.

How do I check the signal without disconnecting the wires?

Most Yokogawa STD4A units with this terminal block include a "Check" terminal or allow enough space for a multimeter probe to touch the clamp plate, allowing you to measure the 4-20 mA loop current in series or the voltage across a precision resistor.

Is this unit compatible with a 3-wire system?

The STD4A is typically a 2-wire transmitter, meaning it draws its operating power from the same two wires used for the 4-20 mA signal.