1554 — Double-Anode Mercury-Vapor and Gas-Filled Rectifying Valve

The 1554 is a heavy-duty, double-anode, mercury-vapor and gas-filled rectifying valve designed primarily for industrial rectifier applications. It is capable of delivering up to 40 A per valve maximum and is suitable for charging or buffering up to 110 lead-acid (Pb) cells.

Filament and Pre-Heating Requirements

The 1554 features a directly heated, oxide-coated filament designed for operation with an alternating current (AC) supply. The electrical requirements for the filament are highly specific, demanding a low voltage and extremely high current:

Because of the mercury-vapor and gas filling, proper pre-heating of the filament is critical before anode voltage is applied. The recommended pre-heating time ($T_w$) is 2 minutes. In urgent situations, this pre-heating period may be decreased to a minimum of 1 minute. To ensure the correct delay is maintained, the use of a type 4152 time delay switch is recommended. Following transport or a prolonged interruption of service, the pre-heating time must be extended to at least 5 minutes to ensure proper distribution of the mercury.

Physical Specifications and Mounting

The 1554 is a physically large and heavy valve, requiring secure mounting and specific orientation to operate safely.

• Mounting Position: The valve must be mounted vertically with the base down.
• Net Weight: 1600 g
• Shipping Weight: 5250 g
• Maximum Dimensions:
  • Height: 355 mm
  • Width: 317 mm
  • Depth/Diameter: 124 mm

The electrical connections are made via specialized terminals and leads to accommodate the high currents:

• The anodes ($a$ and $a'$) utilize M8 threaded connections.
• The auxiliary ignition electrode ($a_h$) uses an M4 threaded connection.
• The filament ($f$) connections are made via heavy flexible leads, measuring 150 mm and 175 mm in length, terminating in 10 mm lugs.

Electrical Characteristics and Auxiliary Ignition

During normal operation, the valve exhibits a typical arc voltage ($V_{arc}$) of 15 V. The typical ignition voltage ($V_{ign}$) is 50 V.

To reliably establish the ignition voltage of 50 V, an auxiliary ignition system is required. An auxiliary DC supply unit capable of delivering approximately 100 V and 25 mA of power must be connected between the auxiliary ignition electrode $a_h$ (connected to the positive terminal) and the cathode (connected to the negative terminal). This connection must be made through a current-limiting resistor to protect the ignition circuit. The Auxiliary Ignition Unit type E3 108 03 is recommended for this application.

Operating Limits and Maximum Ratings

To ensure reliable operation and prevent premature failure, the 1554 must be operated within its strictly defined limiting values:

The operating temperature ($t_{Hg}$) refers to the temperature of the condensed mercury, which must be maintained between 30 °C and 80 °C during operation. The minimum and maximum transformer voltage limits are specified under standard circuit conditions (Circuit a).

Technical Summary

The 1554 is a robust industrial double-anode rectifier utilizing a combination of mercury vapor and gas filling. With a directly heated 1.9 V, 70 A oxide-coated filament, it requires careful pre-heating management, especially after transport or long idle periods. It features a typical arc drop of 15 V and utilizes an auxiliary ignition electrode to facilitate reliable starting at 50 V. Designed for vertical mounting, the valve supports continuous anode currents up to 20 A and peak currents up to 135 A, making it highly suitable for high-power industrial battery charging and rectification systems.