The SPITFIRE buried cable fault locating system consists of a high voltage impulse transmitter, a sensitive earth gradient detector, stainless steel and PVC ground probes, and all necessary interconnecting cables.
Transmitter: The transmitter is a high voltage impulse unit designed to pulse the faulted cable with 960 to 980 volts dc at approximately 5 second intervals. It is housed in a rugged 18g steel carrying case to endure the situations normally associated with fault locating operations. The case measures 16 ¼" by 7 ¼" by 7" and weighs a total of 20 pounds including the detector and cables stored inside.
Input requires 120 volts ac at approximately 150 watts. The only control is the "ON/OFF" switch located on the top panel. A red neon lamp marked "AC" indicates a good 120 volt ac source connection. The transmitter is fused by a 3AG 5 amp fuse located below the AC indicator. An amber incandescent lamp marked "POWER" indicates the transmitter switch is on. The high voltage output circuit is isolated from the transmitter case.
Detector: The detector is a specially designed differential amplifier circuit driving a zero centered dc microammeter for a visual indication of the earth gradient signal. A color coded set of ground probes are provided to collect the signal for the detector. The ground probes can be disassembled and are stored in the transmitter carrying case tool tray. The detector senses the voltage gradient in the earth. The independent probes can be moved farther apart in hard to find faults, helping the detector to differentiate the stronger signal input. All of the controls for the detector are located on it's front panel. It uses a 9 volt alkaline battery for power that can be easily replaced by removing the four front panel screws.
The operating controls are the pushbutton "ON" switch which disconnects the battery circuit when not depressed to prolong battery life. The "BAL" or balance control centers the meter needle prior to investigating a faulted cable. The "SENS" or sensitivity control adjusts the input to the detector. Always begin at zero sensitivity and increase slowly until a ½ scale or good understandable reading is obtained. Only increase if necessary once a good signal is obtained. If the signal diminishes, you could be headed away from the fault and this could be interpreted from the signal weakening.