3-2
BE1-46N Functional Description
NOTE
Connection between relay and meter must be made using no less than a 20 AWG,
shielded, twisted pair with the shield grounded only at the relay case. (Belden
Manufacturing Company part number 9962 or equivalent is recommended.)
analog (D/A) converter. The analog output from the D/A is compared with I
2
by both comparators and the
results sent to the microprocessor. Based on the results of that comparison, another digital number is sent
from the microprocessor to the D/A converter. The analog output is again compared with I
2
and the results
sent to the microprocessor. This continues until the microprocessor number equals the I
2
value. The
microprocessor then compares that number with the selected inputs from the thumbwheels. When the
magnitude of I
2
exceeds the setting of the trip level, the microprocessor begins timing and calculates the
(i
2
)
2
dt. The microprocessor compares the continuously calculated value with the maximum permissible
heating constant K. Tripping occurs when the calculated value exceeds the K setting. If I
2
falls below the
pickup setting, the relay will reset at a linear rate of 2.5 seconds per percent of full scale trip time.
MICROPROCESSOR
BE1-46N relays use an 8-bit, low power, CMS microprocessor which controls all timing, measurements,
computations, and outputs.
PROGRAM MONITOR
During power-up, the program monitor initializes program sequencing. During operation, the microprocessor
outputs a series of pulses at regular intervals. The program monitor senses these pulses and, if the pulses
are disrupted in any way, resets the microprocessor. Reset initializes the program sequence and provides
for fail safe operation.
OUTPUTS
Output relays are provided for trip and alarm functions. An auxiliary output relay is available that operates
at the same time as the trip relay. Trip and auxiliary output relays are available with either normally open
(NO) or normally closed (NC) contacts. The alarm output and oscilloscope start relays are also available
with NO or NC contacts. Power supply output contacts are monitored at the mother board. Normal supply
voltage causes the status relay to be continually energized. However, if at any time the voltage falls below
requirements, the relay drops out, and closes the normally closed contacts.
An optional remote meter calibrated to display the magnitude of I
2
is a percentage of the full load current is
also available. Full scale deflection of the meter corresponds to 50%.
If this option is specified, a standard 4.5 inch switchboard type meter is available and must be ordered
separately. Specify Basler Electric part number 9 1700 00 001.
POWER SUPPLY
Basler Electric enhanced the power supply design for unit case relays. This new design created three, wide
range power supplies that replace the five previous power supplies. Style number identifiers for these power
supplies have not been changed so that customers may order the same style numbers that they ordered
previously. The first newly designed power supplies were installed in unit case relays with EIA date codes
9638 (third week of September 1996). Relays with a serial number that consists of one alpha character
followed by eight numerical characters also have the new wide range power supplies. A benefit of this new
design increases the power supply operating ranges such that the 48/125 volt selector is no longer
necessary. Specific voltage ranges for the three new power supplies and a cross reference to the style
number identifiers are shown in the following table.
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