ALSTOM LE109A-1

Description

Product Overview and Description

The ALSTOM LE109A-1 is a high-speed, auxiliary lockout relay designed for critical protection and control schemes in electrical power systems, often integrated with or adjacent to PLC-based automation. This relay is a specialized spare part, not a standard PLC module, used to provide secure, hardwired interlocking and trip circuit supervision. Its primary function is to receive a trip command from protective relays (like distance or differential relays) or a PLC’s digital output and then securely latch in an energized state to initiate and maintain a circuit breaker trip, close a contactor, or activate an alarm until manually reset. The robust and fail-safe design of the ALSTOM LE109A-1 ensures that once a fault condition is detected, the resulting action is executed and maintained even if the initiating signal disappears. The reliability of the ALSTOM LE109A-1 is paramount for system security, making it a vital component in switchgear, substation automation, and generator protection panels.

Key Parameters and Specifications

• Manufacturer & Series: ALSTOM (now part of GE Grid Solutions).
• Device Type: Electrically Reset Auxiliary Lockout Relay.
• Contact Configuration: Typically features multiple changeover contacts (e.g., 8 or more) with a mix of normally open (NO) and normally closed (NC) configurations. Contacts are silver-plated for high current interruption.
• Coil Voltage: Available in standard DC operating voltages such as 24V, 48V, 110V, or 125V DC. The specific voltage is a critical ordering parameter.
• Reset Mechanism: Electrically reset via a separate reset coil or manually reset via a front-pushbutton, depending on the variant.
• Operating Speed: High-speed operation, typically 10-20 milliseconds, to ensure rapid isolation of faults.
• Continuous Rating: Contacts are rated for continuous carrying current (e.g., 10A) and making/breaking capacities for control circuit duties.
• Mechanical Design: Robust, drawn-case design with a transparent cover for visual indication of the relay’s latched (trip) state. Often features a mechanical “target” or flag that provides a visual indication of operation.
• Mounting: Designed for standard DIN rail or panel mounting.

Advantages and Distinctive Features

The ALSTOM LE109A-1 offers key advantages in security and reliability for protection circuits. Its primary feature is the latching (lockout) mechanism, which ensures that a trip command is “sealed-in” until a conscious manual or electrical reset is performed, preventing automatic re-closure onto a fault. The high contact capacity allows it to directly interrupt trip coil currents and simultaneously operate multiple indicators, alarms, and remote signaling circuits. The relay’s robust mechanical construction ensures reliable operation over thousands of cycles and in harsh substation environments with vibration and wide temperature ranges. The visual target flag on the ALSTOM LE109A-1 provides immediate local indication of which protection function operated, a crucial feature for post-fault analysis. Its fail-safe design philosophy means that a loss of control power will not cause an unintended reset, maintaining the safety state.

Application Cases in Key Fields

• Substation Protection: Used as the central lockout relay in a transmission line protection scheme. When a line protective relay trips, it energizes the ALSTOM LE109A-1, which latches in to hold the circuit breaker open, send a trip signal to the remote end (via PLC/telecontrol), and illuminate local and remote alarms until the fault is investigated and the relay is reset.
• Generator Protection: Acting as the 86G (Generator Lockout) relay. Upon detection of a stator ground fault or loss of excitation, the protection system trips the generator breaker and field breaker via the latching contacts of the ALSTOM LE109A-1.
• Busbar Protection: Serving as the common trip relay for a bus differential scheme, ensuring all connected circuit breakers are opened and locked out in the event of a bus fault.
• Industrial Power Distribution: Providing a secure, hardwired master trip function for a large motor or feeder protected by a multifunction relay, independent of the PLC’s scanning cycle for ultimate safety.

Comparison with Competing Products

The ALSTOM LE109A-1 competes with similar electromechanical lockout relays from other protection manufacturers like Siemens (3TX series) or Schneider Electric. Its design is a classic, proven technology. Compared to a standard PLC output relay module, the ALSTOM LE109A-1 provides dedicated, hardware-based latching logic, superior contact ratings for inductive loads like trip coils, and a visual mechanical flag—features not found in a typical PLC rack. It is often used in conjunction with a PLC; the PLC may initiate the trip signal, but the ALSTOM LE109A-1 executes the secure, latching action. Software-based latching in a PLC does not provide the same level of independence, visibility, and contact durability for this critical function.

Selection Suggestions and Precautions

Selection Suggestions:

1. Select the ALSTOM LE109A-1 as a direct replacement for a failed lockout relay in an existing protection panel, ensuring the coil voltage and contact configuration match the original specifications exactly.
2. It is the appropriate choice for new designs where a secure, visible, and hardwired latching function is required by electrical safety standards or protection engineering practice.
3. Choose the electrically reset or manually reset variant based on the control scheme design (remote vs. local reset requirement).

Important Precautions:

1. Coil Voltage Matching: Critically, verify the DC coil voltage (e.g., 110VDC vs 125VDC) of the existing relay and order the ALSTOM LE109A-1 accordingly. Applying an incorrect voltage can burn out the coil or fail to operate the relay.
2. Contact Rating Verification: Ensure the contact current ratings are suitable for the loads they will control (e.g., breaker trip coils can have high inrush currents). Do not exceed the make/break capacity.
3. Reset Circuit Design: If using the electrically reset variant, design the reset circuit with appropriate interlocks to prevent accidental or automatic reset while personnel may be investigating the fault.
4. Mechanical Inspection: After installation, manually test the latching and reset mechanism, and verify the visual target operates correctly.
5. Integration Testing: After replacement, the entire protection scheme including the new ALSTOM LE109A-1 must be functionally tested with primary injection or simulated fault signals to verify correct operation and sequencing with breakers and other relays.

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