R115
R62
R63
C91
C92
R7
C78
C75
R5
R6
U16
SM73201MM
VREF
ADC_CLK
ADC_CS
ADC_DATA
5V
L9
3.3V
L11
ADC_INPUT
VA
VIO
DOUT
GND
GND
VREF
+IN
-IN
SCLK
CSB
+V
+
-
R133
Q1
Q2
C15
R18
R17
C12
R19
U4B
C14
+
-
R20
R21
VREF
R16
C11
C10
SELF_TEST
U4A
5V
J9
R23
R22
NOISE_EN
SW1
Differentiation of Series and Parallel Arcing Events
Figure 8. Self Test Circuit
The A/D converter is a 16bit converter operating at approximately 250kS/s. The high resolution translates
to a high dynamic range for the sensed signal, thereby allowing the arc signature to be sensed properly
without clipping due to the potentially higher amplitude of interference signals from the inverter. The
converter sampling rate is controlled by the microcontroller. The connection is shown in
Figure 9. A/D Converter
15
Differentiation of Series and Parallel Arcing Events
There are two main types of electrical arcing events in PV systems: Series arcs and Parallel arcs. Series
arcing events occur when the current path is opened and the breakdown voltage for the opening is
exceeded. These are caused by any type of incomplete connection; examples include cold solder joints,
conductor corrosion, and improperly mated connectors.
10
AN-2154 RD-195 DC Arc Detection Evaluation Board
SNOA564F – June 2011 – Revised December 2012
Copyright © 2011–2012, Texas Instruments Incorporated
