71M6403
Electronic Trip Unit
SEPTEMBER 2006
Processed Current Data
Processed current data is available in CE addresses 0x4A through 0x4F, as listed below:
Output
CE Address
Description
Register
I0SQSUM_X
I1SQSUM_X
I2SQSUM_X
I3SQSUM_X
I4SQSUM_X
I5SQSUM_X
0x4A
0x4B
0x4C
0x4D
0x4E
0x4F
LSB = (IMAX/ln8)2 * 3.3335*10-8 A2 peak
LSB = (IMAX/ln8)2 * 3.3335*10-8 A2 Peak
LSB = (IMAX/ln8)2 * 3.3335*10-8 A2 Peak
LSB = (IMAX/ln8)2 * 3.3335*10-8 A2 Peak
LSB = (IMAX/ln8)2 * 3.3335*10-8 A2 Peak
LSB = (IMAX/ln8)2 * 3.3335*10-8 A2 Peak
The CE writes the output data into the I0SQSUM_X, I1SQSUM_X etc. registers at the end of each accumulation interval.
The values for IXSQSUM_X are based on the formula:
STR _ CNT +1
IXSQSUM _ X =
IXSQ
∑
0
Overcurrent Detection
The main task in circuit breaker applications is to detect an over-current situation as quickly as possible and to apply the tripping
procedures. The CE firmware has an integrated comparator function that helps to verify each measured sample with reference to
the value stored in the FAULT_THRESH register at address 0x2F. If a sample above the programmed FAULT_TRHESH is
encountered in one of the input signals I0, I1, I2 or I3, the FAULT_PULSE is generated on the DIO7 pin. This pin should be
configured by the MPU to be an output pin and should be internally set to generate an interrupt in order to initiate the necessary
routines of the circuit breaker application firmware. The process for generating the FAULT_PULSE from encountering a sample
above the programmed threshold can be less than 400µs.
CE Register
FAULT_THRESH
STR_CNT
CE Address
0x2F
Description
LSB = (IMAX/ln8) * 5.5719*10-9 A peak
STROBE_PULSE =
0x31
(STR_CNT + 1) * 3.9673*10-4 s
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© 2006 TERIDIAN Semiconductor Corporation
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