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CALIBRATION CERTIFICATE
BCH-2 Cable Identifier
INTRODUCTION
Before repair work can commence on
an underground cable, the cable must be positively identified. Many manholes and vaults
contain numerous runs of cable and it is imperative that the repair crew does not cut into
an energized cable instead of the damaged de-energized cable. This requirement serves as
justification for the existence of a cable identifier.
The BCH-2 has the following qualities, which make it an ideal cable-Identifying instrument:
TRANSMITTER
The BCH-2 cable Identifier was
developed for use on three phase non-ferrous distribution cables such as PILC belted or
XPLE concentric neutral.
The battery powered transmitter generates a 300 V DC pulse which is applied to the "B" and "C" phase of the cable under test, the other end of the cable is terminated by a suitable jumper across "B" and "C" phase of the cables.
The polarity of the DC pulse depends on the direction of the current flow; "B" phase will have a DC pulse opposite in polarity to that of "C" phase
REMOTE TURN OFF
The transmitter has an added
feature of "Remote Turn Off". "A" phase is used for this purpose and
is usually connected at the same time as "B" and "C" phase.
As a cable is being cut, a momentary short between "A" and "B" or "A" and "C" phases automatically stops the transmitter and removes the open circuit DC voltage.
PHASING
The transmitter has provisions for
phasing. After a cable has been cut a diode is switched across "B" and
"C" phases inside the transmitter enabling phasing in both directions at the
work site.
BATTERY CHARGER
The transmitter has a built in
battery charger for the two sealed lead acid batteries that are within the instrument
case. A charged transmitter battery will give approximately eight hours of operation.
RECEIVER
The cable identifier receiver is a
hand held battery operated solid state device and works in conjunction with an external
pick-up coil probe that has been shielded to restrict pick-up to the sensing side of the
probe only.