DPR-400 User Manual Rev_01 Firmware V-1.0
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There are 4 levels of configuration parameters for negative component overcurrent. This allows for
configuring different trip timers for different input currents. For example, level 1 (I2>) protection may be
programmed for negative component overcurrent, while level 2 (I2>>) can be used for short circuit
protection with sudden trip (constant time (DT) and trip timer set to 0).
The controller allows directional protection for negative component overcurrent. It can be used for single
directional protection, or level 1 (I2>) protection can be programmed for forward directional protection
while level 2 (I2>>) can be configured for reverse directional protection.
If the voltage and current of one phase are in the same direction, the current is flowing from the source to
the load, which means it is forward directional. If the voltage and current of one phase are in opposite
directions, the current is flowing from the load to the source, which means it is reverse directional.
Protections can be configured directionless or for either of these directions.
As explained in the “OVERCURRENT PROTECTION (ANSI 50/51)” section, protections can be
configured as directional. In addition, different levels of protection can be configured for forward and
reverse directions.
Broken conductor can be recognized basically from the unbalance in the forward and reverse directional
components of current (I2/I1). Here, I2 is the reverse directional current component and I1 is the forward
directional component of the current. If one of the phase wires is broken, which means its current value is
0, the I2/I1 ratio becomes 50%. This protection can also be used for unbalanced loading protection
purposes.
Two fundamental values determine the configuration of this protection:
1. Current threshold value (% I2/I1)
2. Trip timer (sec)
The CT supervision feature operates on detection of derived zero sequence current, in the absence of
corresponding derived zero sequence voltage that would normally accompany it.
If the ground current exceeds the configured threshold, this function begins calculating the trip timer for
the given parameters. This output trips the breaker at the end of the configured timer. This protection can
be configured as constant time (DT) or variable time (IDMT).
There are 2 levels of configuration parameters for ground overcurrent. This allows for configuring different
trip timers for different input currents. For example, level 1 (IN>) can be used for overcurrent protection
while level 2 (IN>>) can be used for short circuit protection with sudden trip (constant time (DT) and trip
timer set to 0).
9.5. DIRECTIONAL OVERCURRENT PROTECTION (ANSI 67)
9.6. BROKEN CONDUCTOR (ANSI 46BC)
9.7. CT SUPERVISION (ANSI 74CT)
9.8. GROUND OVERCURRENT PROTECTION (ANSI 50N/51N)