ABB DPU 1500R Instruction Book page 14

Another thing that can keep the relay from reclosing, regardless of what the settings are, is the way the unit is tested.
When the relay is tripped, the breaker status 52A (XO) and 52B (XI) contacts must change state and the fault current
must drop to 5% under the lowest pickup within the Trip Failure Time setting or the relay will go to Lockout and issue
a breaker failure alarm. The breaker status requirement can be bypassed by putting the relay into Functional Test mode
(from the Test Menu). In this mode, the relay can ignore the status of the 52A (XO) and 52B (XI) contacts for 15 minutes,
unless it is reset.
To stop the fault current, the current source should be configured to turn off when it senses that the trip contact has
closed, or, the current could be wired through an A-contact controlled by the breaker. If the current cannot be turned
off quickly enough, the Trip Failure Time setting (in the Configuration Settings group) can be increased up to 1
second (60 cycles).
There are additional reasons that the DPU1500R relay may not reclose when the relay does not contain only factory
settings. Some possible causes are listed here:
1. The function that causes the trip is set to send the relay into "Lockout" within the 79-X (O->IX) Select setting where
X can be reclose step 1, 2, 3, 4 or 5.
2. The 79V (O->IU<) Voltage Select setting is enabled and one of the phase voltages is below the 79V (O->IU<)
Pickup setting.
Introduction
ABB Distribution Protection Unit 1500R
Page xiii