Regulus uREG, User Manual

Page: 103 / 107

uREG User Manual
103
18. FAULT TROUBLESHOOTING
Unit faults can be generally divided into three classes:
1. abrupt faults caused by irreversible damage to one or more component(s), which prevents
further operation of the device,
2. parametric faults caused by ageing or partial wear of components – gradual deterioration of
device quality,
3. temporary faults caused by external or internal mechanical interruption, electromagnetic
interference or due to errors in device software.
The following selection of recommendations for the measures in the event of fault (or
suspected fault) concerns allowed actions to be taken by the operator.
→ Re 1:

The controller is shut down (no signs of power supply) – Check the T0.5A fuse in the PS-
0 module; if the fuse is burnt, a single attempt to replace it with an operational fuse is
acceptable.

The controller is supplied but the power LED is off – Record signs of the observed
condition and make an attempt to reset the device by short (approx. 5 s) disconnection
from auxiliary power supply.

No recognition of the peripheral module based on the notification on the LCD screen –
Once auxiliary supply is disconnected, make an attempt to replace the faulty module
with an identical one.
If failed, please contact the manufacturer for assistance.
→ Re 2:
Most frequently, parametric faults of this class relate to two groups of circuits: measurement
paths relating to analogue values (currents, voltages, temperatures, etc.) and sensitivity
thresholds for digital inputs.
Current and voltage measurement paths are pre-adjusted for requirements ensuring
indications within the proper accuracy class, at the final manufacturing stage of current and
voltage transformer modules. For this purpose, instrument transformer boards are equipped
with trimming potentiometers used to minimize measurement errors at selected characteristic
curve points:

for indications of CT-0 phase currents Ik = 2.0 A,

for indications of earth-fault currents I0k = 0.5 A,

for VT-0, VT-2, VT-3 phase currents Uk = 64.0 V,

for the zero sequence voltage U0k = 20.0 V.
Consequences of imperfect pre-adjustment using potentiometers as well as ageing and
ambient temperature effects can be additionally eliminated by the computer-based calibration
mechanism dedicated to measurement paths. The mechanism is built in procedures of the
system functor (called
KOREKTY / CORRECTIONS ). The functor provides a numerous group of
corrective coefficients (‘p’), which are time-varying (-128, +127), which determine resulting