ABB RET670 Commissioning Manual page 209

1MRK 504 165-UEN A
Transformer protection RET670 2.2 IEC
Commissioning manual
Testing functionality by secondary injection
• UL1: Ampl = 50 / √3; Angle = 0°
• UL2: Ampl = 50 / √3; Angle = 240°
• UL3: Ampl = 100 / √3; Angle = 120°
Last section of the characteristic:
If VDepMode = either Slope or Step, the minimum measured phase-to-phase
voltage is higher than UHighLimit/100*UBase:
• UL1: Ampl = 105/ √3; Angle = 0°
• UL2: Ampl = 105/ √3; Angle = 240°
• UL3: Ampl = 105 / √3; Angle = 120°
4. Inject the voltages that are related to the first part of the characteristic, and
then slowly increase the phase current IL1 from 0.0 A up to the value the
function operates. The START and STOC signals must be activated when the
amplitude of the phase current IL1 is slightly above 0.25 A on the secondary
side. The corresponding trip signals TROC and TRIP will be activated after
the pre-set time delay has expired.
5. Decrease the current IL1 slowly and note the reset value.
6. Repeat steps 4 and 5 applying voltages that are related to the second and the
last section of the characteristic; the function operates when IL1 is slightly
higher than: 0.5 A in the second section; 1A in the last section.
7. Connect the trip output contact to the input channel of the test set in order to
stop the injection and measure the trip time.
8. If definite time delay is used for the overcurrent step, set the setting
Characterist = IEC Def. Time. Apply the voltages related to the last part of
the characteristic and inject a current IL1 200% higher than the set operation
level, and check the definite time delay for trip (the signals TROC and TRIP
of the protection function VRPVOC are active in trip condition).
9. If inverse time delay is used for the overcurrent step, the parameter setting
Characterist shall be properly set; we can refer, for example, to the setting
IEC Very inv.; If the IEC Very inverse time characteristic is selected, the trip
signals TROC and TRIP will operate after a time defined by the equation:
13 5 . * k
t s
[ ]
=
I
 
1
 −

StartCurr
 
IECEQUATION2435 V1 EN-US
where:
t Operate time in seconds
I Measured value (for example, phase current)
StartCurr Set operate value
This means that if the measured phase current jumps from 0 to 2 times the set
operate level and time multiplier k is set to 1.0 s (default value), then the
TROC and TRIP signals will operate after a time delay equal to 13.5 s ±
tolerance.
Section 11
(Equation 94)
203