Allen-Bradley E300 - Voltage Imbalance Protection

Rockwell Automation Publication 193-UM015E-EN-P - October 2015 373
Protective Trip and Warning Functions Chapter 6
Voltage Imbalance Protection
A voltage imbalance can be caused by poor power quality and unequal
distribution of power. When a voltage imbalance exists, the motor can experience
an additional temperature rise, resulting in degradation of the motor insulation
and reduction of life expectancy. The E300 relay can monitor for this condition
with its Voltage Imbalance Trip and Warning function to detect for a rapid
voltage imbalance fault to minimize damage and loss of production.
Voltage Imbalance can be defined by the following equation:
%V
Imb
= 100% * (V
d
/V
a
)
where
%V
Imb
= Percent Voltage Imbalance
V
d
= Maximum Deviation from the Average Voltage
V
a
= Average Voltage
Voltage Imbalance Inhibit Time
Voltage Imbalance Inhibit Time (Parameter 365) allows you to inhibit a voltage
imbalance trip from occurring during the motor starting sequence. It is adjustable
from 0…250 seconds.
Table 298 - Voltage Imbalance Inhibit Time (Parameter 365)
Voltage Imbalance Trip
The E300 relay trips with a voltage imbalance indication if:
• No trip currently exists
• Voltage Imbalance Trip is enabled
IMPORTANT
The Over Voltage Warning function does not include a time delay feature. Once
the Over Voltage Inhibit Time has expired, the Over Voltage Warning indication
is instantaneous.
Default Value 10
Minimum Value 0
Maximum Value 250
Parameter Type USINT
Size (Bytes) 1
Scaling Factor 1
Units Seconds