4 Protection settings
4.9 Maintenance mode (ARMS)
30
PXR Electronic trip unit
01/21 MN012005EN
www.eaton.com
4.9 Maintenance mode (ARMS)
The PXR25 trip units support Eaton’s Arc Flash Reduction Maintenance
System™ (ARMS). This is also known as the maintenance mode. If enabled,
the trip unit will trip the circuit breaker with no intentional delay whenever
the configured threshold value is exceeded. If enabled, the maintenance
mode will operate independently of the overload and short-circuit protection
settings. If the maintenance mode causes the circuit breaker to trip, the
message “ARMS trip” will be displayed, provided that auxiliary power is
available.
The maintenance mode is configured either via the display and the navigation
buttons, or via USB or the communication link. The settings allow for
different protection levels.
The following settings are available:
•
2.5 x I
n
•
4 x I
n
•
6 x I
n
•
8 x I
n
•
10 x I
n
A higher protection level may be required if, for example, the circuit breaker
protects another load with motors that need to be started, and which
generate high inrush currents above the lowest trip-current level.
The maintenance mode offers protection against arc faults with low current
values, which due to impedance do not reach the threshold value of the
instantaneous short-circuit release. ARMS will recognize these currents as
an immediate danger and will switch off without any delay, thereby reducing
the energy released in the event of an arc fault. This also offers effective
protection for maintenance personnel in the vicinity.
Activating the maintenance mode
There are three options for activating the maintenance mode:
•
locally via the display,
•
remotely via a contact,
•
remotely via the communication interface.
The LCD display will indicate if the function is activated, and this information
can also be read out via the communication link.
To activate the maintenance mode locally, use the display and the control
buttons on the trip unit. If the maintenance mode has been activated locally,
remote deactivation is not possible. The maintenance mode can only be
deactivated via the same channel through which it was activated (for
example, locally if it was activated locally).
→
The reduction settings should be determined by an individual
with experience in power system analysis.