Atec Megger-BGL - Manual

BGL
Battery Ground-Fault Locator
■
Locates ground faults on floating
battery systems
■
Operates on live battery systems
■
Multiple fault detection and tracking
■
Automatic operation
■
Battery operated
BGL
Battery Ground-Fault Locator
DESCRIPTION
The Battery Ground-Fault Locator (BGL) simplifies the
tracking of ground faults on floating dc-powered control
systems.
It features automatic operation, can be used on live battery
systems and has the unique capability of detecting,
tracking and locating multiple faults on a battery system
without having to resort to sectionalizing.
This is accomplished by injecting a low- amplitude 25
Hertz test signal on either the positive or negative side of
the power bus and tracking the signal with one of several
available clamp-on sensor probes.
A fault simulator also is provided with the instrument,
allowing the periodic verification of the resistance and
capacitance ranges of the BGL.
APPLICATIONS
The BGL allows tracking and locating of ground faults on
live or dead battery systems. Its locating ability is only
limited by the accessibility of the battery cable.
The instrument can make measurements in the presence of
dc current (up to 20 amperes) and ac ripple (charging
current up to 0.5 ampere).
The BGL is useful for locating grounds on any type of
battery system, including those in refineries, mines and
utilities as well as UPS and continuous process systems.
The BGL operates on battery systems that are either
floating or grounded through a resistor. Operators can
determine both the direction and magnitude of faults,
allowing them to ignore high-impedance faults and
concentrate on serious faults.
The BGL is designed to work on battery systems up to 260
volts dc. The instrument even operates in the presence of
surge-suppression capacitors, effectively ignoring them. It
is only sensitive to the power dissipated in the grounding
resistance, hence the resistive paths to ground.
An additional feature of the BGL is its ability to measure
battery system total capacitance to ground, or the
capacitors of any branch of the system. This allows the
operator to determine the maximum practical fault-
resistance range and provides the user with information on
the battery system.
PRINCIPLE OF OPERATION
The instrument operates by injecting a 25 Hertz signal
between the battery system and the ground. The resulting
current is tracked by a clamp-on current probe. The
magnitude of the injected signal is only 3.5 volts and will
not cause any interference with the operation of sensitive
protective relays on the system.
The instrument’s circuitry measures the 25 Hertz power
dissipated in the grounding resistance and calculates the
value of the grounding resistance from knowledge of the
applied voltage.
This method allows the instrument to effectively eliminate
the effects of charging current due to capacitance on the
battery system or surge suppression capacitors that may be
installed on the system.