340 Rockwell Automation Publication 193-UM015E-EN-P - October 2015
Chapter 6 Protective Trip and Warning Functions
Line Undercurrent Protection
For non-motor applications, if the measured current is less than a specific level for
a specific phase, it may indicate an electrical malfunction, such as bad resistive
heater element or non-operating incandescent light bulb. Such conditions may
not harm the power system, but it can lead to loss of production or certification
noncompliance.
The E300 relay can monitor for an undercurrent condition per phase with its
Line Under Current Trip and Warning function to detect for a rapid under
current in a specific phase to minimize damage and loss of production.
Under Current Inhibit Time
Under Current Inhibit Time (Parameter 265) allows you to inhibit an L1, L2,
and L3 Under Current trip and warning from occurring during a load starting
sequence. It is adjustable from 0…250 seconds.
Table 262 - Under Current Inhibit Time (Parameter 265)
L1 Under Current Trip
The E300 relay trips with a L1 Under Current indication if:
• No trip currently exists
• L1 Under Current Trip is enabled
• Current is present
• Under Current Inhibit Timer has expired
• L1 Percent FLA (Parameter 47) is less than the L1 Under Current Trip
L
evel
for a time period greater than the L1 Under Current Trip Delay.
• If the E300 relay trips on a L1 Under Current, the:
• TRIP/WARN LED status indicator flashes a red 8-short blink pattern
• Bit 7 in Current Trip Status (Parameter 4) sets to 1
• Bit 0 in Device Status 0 (Parameter 20) sets to 1
The Current Imbalance Warning function does not include a time delay feature.
Once the Current Imbalance Inhibit Time has expired, the Current Imbalance
Warning indication is instantaneous.
Default Value 10
Minimum Value 0
Maximum Value 250
Parameter Type USINT
Size (Bytes) 1
Scaling Factor 1
Units Seconds
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