| AVO / Megger / Multi-Amp CB-845 Circuit Breaker Test Set
The Megger CB-845
test set is a high-current circuit breaker test
set consisting of a control unit that incorporates the latest
in solid-state metering, control technology and a high-current
output unit. The lightweight, two-section
design of Megger CB-845 enables the user to
easily transport the unit into areas previously
inaccessible to high-current test equipment such as
elevated or subsurface load centers, shipboard power panels,
elevator machinery rooms and other isolated locations.
The Megger /
Multi-Amp CB-845 is suitable for a wide variety of testing requirements
including molded-case circuit breakers; thermal,
magnetic or solid-state motor overload relays and other
overcurrent protective devices. Additional applications
include verifying the ratio of current transformers
and testing ground-fault trip devices. The
time-delay characteristics of motor overload relays and molded-case
circuit breakers rated up to 500 amperes can be
tested with the CB845, when following the recommended
test procedure of testing the time delay of thermal
devices at three times their rating. Instantaneous trip
elements can be tested with the higher currents required
for these tests. For example, the test set will provide
short-duration output of 5000 amperes through a typical
500 ampere, molded-case circuit breaker.
Features:
-
Digital memory
ammeter: High-accuracy, direct reading instrument
features read-and-hold memory for measurement
of short-duration currents.
-
Digital,
multirange timer: Crystal controlled, high accuracy instrument
measures operating time to 1 ms.
-
Lightweight and
portable: Two-section unit has a total weight
of only 175 lb (80 kg).
-
High output
current: Provides instantaneous current up
to 5000 amperes through a 500 ampere circuit breaker.
-
Solid-state
output initiate circuitry: Solid-state output circuit
switching eliminates need for contact maintenance.
-
Protection:
Overload and short- circuit protection is incorporated.
-
Enclosure: The
test set is housed in two stackable,interlocking,
rugged, metal enclosures with convenient carrying
handles. The control unit comes with a lid for protection
of the controls during transportation. The unit is
easily transported by and/or on a standard handtruck.
Specifications:
Input
Input Voltage (switch-selected): 208
and 240 V, 1φ, 30 A
Input Frequency (specify one): 50 Hz OR 60 Hz
Output
Output Range:The
output is continuously adjustable to accommodate a variety of test
circuit impedances: 0 to 1200 A at 6 V max.
Output Capacity
The output circuit is designed
to provide short-duration overloads. The
above output range will provide several times its current rating,
provided the output voltage is sufficient to push the desired
current through the impedance of the test circuit. The
test set is capable of testing the time-delay characteristics of devices
rated up to 500 A using a test current of three times their rating
(1500 A). Additionally, to perform an instantaneous trip test, it
will provide 5000 A through a typical 500 A, molded-case circuit breaker
connected with the 4 ft (1.2 m) test-leads provided.
Overload Capability
To increase use of the test set, it is designed so that the current ratings may be exceeded for short
durations. Because the magnitude of
the output current is determined by the impedance of
the load circuit, the voltage rating must be sufficient to push the
desired current through the device under test and the connecting
test leads.
Output Initiate Circuit
The test set uses a solid-state output initiating circuit. To increase reliability and eliminate contact
maintenance, this circuit uses a triac
instead of a contactor to initiate the output.
Output Initiate Control
Circuit
The initiating control circuit provides momentary and maintained modes
to control output duration. The momentary mode is used whenever
the output is to be on for a short duration. An example is
an instantaneous trip test, or to avoid damage or overheating of the
device under test while setting the test current. In the maintained
mode, the output remains energized until manually turned
off, or when performing timing tests, until the device under
test operates which both stops the timer and de-energizes the
output.
Timer: A
solid-state digital timer measures the elapsed time of the test in either
seconds or cycles. It uses a crystal controlled oscillator and therefore,
its accuracy is independent of the line frequency.
Display: 5-digit,
extra-bright LED display with 0.3 in. (7.62 mm) numerals
Ranges (switch-selected)
0 to
99.999 s
0 to 999.99 s
0 to 99999 cycles
Accuracy: ±0.005%
of reading, ±1 digit |
