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11. Recloser/circuit-breaker condition monitoring
For continuous knowledge of the operational avail-
ability of recloser/circuit breaker, the RER620 fea-
tures a comprehensive set of monitoring functions.
Everytime the recloser/breaker operates, there will
be electrical and mechanical wear. Thus, the life of
the recloser/circuit breaker reduces due to wear-
ing. The wearing in the recloser/breaker depends
on the tripping current, and the remaining life of
the recloser/breaker is estimated from the re-
closer/breaker trip curve provided by the manufac-
turer. The remaining life is calculated separately for
each phase and it is available as a monitored data
value.
The recloser/breaker monitoring can include check-
ing the wear and tear of the recloser/circuit
breaker, the spring charging time of the breaker
operating mechanism and the gas pressure of the
breaker chambers. The protection and control relay
also monitors the breaker travel time and the num-
ber of circuit breaker (CB) operations to provide
basic information for scheduling CB maintenance.
12. Trip-circuit monitoring
In the case RER620 is used with a breaker, the
trip-circuit monitoring continuously supervises the
availability and operability of the trip circuit. It pro-
vides open-circuit monitoring both when the cir-
cuit breaker is in its closed and in its open position.
It also detects loss of circuit-breaker control volt-
age. Local and remote indication are programma-
ble to ensure immediate notification so the neces-
sary steps can be established to correct before the
next fault event occurs.
13. Self-diagnostics
The protection and control relay’s built-in self-diag-
nostics system continuously monitors the state of
the protection and control relay hardware and the
operation of the relay software. Any fault or mal-
function detected will be used for alerting the op-
erator. A permanent protection and control relay
fault will block the protection functions of the relay
to prevent incorrect relay operation.
14. Fuse failure protection
The protection and control relay includes fuse fail-
ure supervision functionality. The fuse failure su-
pervision detects failures between the voltage
measurement circuit and the relay. The failures are
detected by the negative sequence based algo-
rithm or by the delta voltage and delta current al-
gorithm. Upon the detection of a failure the fuse
failure supervision function activates an alarm and
blocks voltage-dependent protection functions
from unintended operation.
15. Uninterruptable Power Supply (UPS)
The UPS unit is used in conjunction with RER620.
Although the UPS is a physically separate unit, it is
connected to and is controlled by the RER620. An
external battery needs to be connected to the UPS,
such that the UPS can draw power from the battery
and make it available to the RER620, as well any
other auxiliary devices, in the event the main power
source is lost. The UPS charges the battery and also
tests the battery to ensure its health and availabil-
ity.
The UPS may be powered by AC or DC. There are
two variants of the UPS. One variant covers the
125VDC and 120VAC range and another variant cov-
ers the 250VDC and 240VAC range. The UPS is
equipped with the ability to monitor the availability
of input voltage if powered by AC. In the case the
main AC supply is lost, alarm is provided locally to
the local HMI as well as remotely.
The UPS has an isolated Auxiliary Power Supply for
auxiliary equipment such as radios, modems, etc.
The Auxiliary Power Supply has two output voltage
settings, 12VDC and 24VDC.
The UPS has an integrated battery charger that is a
current regulated charger. The battery voltage de-
termines when the charger is switched off. The
switch off voltage is influenced by the temperature
to some degree. The battery charger may charge as
high as 50 W, but this is limited by the firmware and
presently set to a value less than 50 W. The output
wattage varies through different portions of the
charge curve. If the battery to be charged is com-
pletely discharged or close to being completely
dead then only a small amount of charge current is
applied to the battery. As the battery starts
charging, indicated by a voltage increase, the cur-
rent is increased. This method is used to prevent
battery charge failure due to trying to charge a de-
fective battery or shorted battery circuit. The UPS
has a circuit that switches in 1.5 ohms, 40 W of re-
sistance across the battery. This load is applied to
the battery for 0.1 seconds. The battery’s voltage
-is taken before and during this time. A comparison
of the two measurements can be made and the
health of the battery determined.
The UPS has embedded boost circuit for driving
magnetic actuator of ABB GridShield reclosers. The
output from this boost supply provides the power
to operate the actuators for the GridShield family
of reclosers.
