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FS-17 Firing System
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DESCRIPTION
The RISI FS-17 EBW firing system is designed for field firings where (1) there is no 110 or 220 VAC power available, (2) where the actual module voltage must be monitored and (3) where instantaneous firing or external triggering is required. The system consists of a Control Unit (P/N 167-8917) and a Firing Module (P/N 167-8371). The system also includes a battery voltage meter, keyed arm switch and coaxial output connector on the module. (operation discussion)

Design and Specifications
Input Energy
  • Battery supply for a minimum of 50 firings.
  • Built-in battery charger for 110 VAC
  • (220 available)

Output Energy

  • 4000 volt pulse with 1500 amperes peak current into low resistance load (8.0 joules).

Circuit

  • Regulated DC battery power supply in Control Unit.
  • DC to DC converter with high voltage energy storage capacitor in firing module
  • Triggered gap for instantaneous firing (typically less than 10 microseconds)
  • Meters in Control Unit to monitor module capacitor voltage and battery voltage
  • External or internal trigger monitor

Control Unit Input Connection

  • U.S. Type, 3 pin plug for 110 VAC battery recharging
  • (Special plug for 220 VAC if required)
  • Safety interlock and Key Arm Switch to arm
  • Meter to indicate module arm voltage & discharge rate
  • Five-pin connector to module
  • Six-pin connector for accessory connection for ‘Pulse Out’
  • External trigger pulse out
  • External switch closure
  • External breakwire
  • Automatic trigger
  • Meter to indicate battery voltage
  • External dimensions: 6”x7”x9”

Control Unit to Module Connection

  • Requires 3-Conductor Shielded Cable with ground
    used as a shield
  • Maximum 2,000 feet of 20 gauge wire

Module

  • Five pin connector for connection from Control Unit
  • Safety Interlock Connector
  • Reynolds Type 31 Coaxial output connector

Module to Detonator Connection

  • Maximum 100 feet twin lead blasting wire (P/N 167-8559)
  • Maximum 300 feet Type “C” high voltage coaxial cable (P/N 167-2669)

Options

  • FS-46 Ruggedized Module P/N 188-7065
  • FS-46 Underwater Pressure Sealed Module P/N 188-7138

FS-17 Operation Discussion
The purpose of the FS-17 Control Unit is to provide low voltage electrical energy to the Firing Module and to ensure a safe and reliable operation sequence for the firing of EBW detonators.

The output from the Control Unit to the Firing Module is 40 volts when the batteries are fully charged. This output occurs when the “Arm” switch is held in the “Arm” position and the shorting plug is mated into the Control Unit “Safety Interlock” connection. When the “Test” switch is pulled, the battery voltage will be displayed on the battery meter. The battery should provide a minimum of 32 volts to properly operate the system. When the system is “armed,” the “Firing Volts” meter will display the high voltage from the Firing Module. The high voltage must be at least 3500 volts before firing is initiated.

The purpose of the FS-17 Firing Module is to provide a significant amount of flexibility to this EBW detonator firing system. Since the firing pulse to function the EBW detonator must be applied with a rapid pulse rate of rise, the Firing Module must be placed relatively close to the detonator. By being able to separate the Firing Module from the Control Unit, the operator can perform the detonation at extended distances as required by the size and characteristics of the main explosive charge.

The input voltage to charge the Firing Module must be between 32 and 40 volts. This low voltage input enables the Module circuitry to charge a one microfarad capacitor. When this capacitor reaches 4000 volts, the Firing Module is ready to be fired. Triggering of the triggered spark gap occurs by applying a 30 volt pulse to the Module. This discharges the one microfarad capacitor into the coaxial output connector which, if properly connected, will fire the EBW detonator. Detonation will occur in less than 10 microseconds from the time that the 30 volt trigger pulse is applied to the Module.

By mating the shorting plug to the “Discharge” connector, the energy storage capacitor is completely and immedi-ately discharged thus precluding inadvertent arming of the Firing Module and detonation of the EBW detonator.

Caution: While EBW and EFI Initiators are inherently less susceptible to accidental detonation during handling and set-up than devices containing primary explosives, electrical and electronic firing systems are sensitive to transient electrical energies which could cause premature triggering or firing. The blasting area must be clear of personnel and equipment before the detonator leads are connected to any RISI Firing System. Only approved RISI Firing Systems should ever be used to initiate or detonate any explosive product manufactured and authorized for sale by RISI.