Basler BE1-CDS220, Instruction Manual

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BE1-CDS220 Testing And Maintenance 13-41
Sidebar 13-8. Determining the Operating Point on the Curve
I
restraint at balance
< > minpu x






−
1
100 / slope
1
in per unit
1 < (0.35 * ((1/0.15)-1))= (0.35 * 5.67) = 1.98 per unit
where: The operating point is on the flat part of the curve.
Thus, we use the following to derive the trip condition. Notice the added multiples of tap variable which we
know in this case is 1.5 times tap or, 1.5 per unit.
I
2trip min
= I
2balance
+ minpu * multiples of tap in per unit
I
2trip min
= 1 + 0.35 * 1.5 = 1.53 per unit
where: I
2 current
(@ 2 x tap) = tap X I
2trip min
= 2.00 * 1.53 = 3.05 amps
Because 1.53 per unit is less than 1.98 per unit, we know that our trip point is on the flat part of the curve
and the applied current is actually 1.5 pu.
Step 1. Connect one current source to terminals B1, B2 (A-phase, input 1) and a second current
source to terminals B9, B10 (A-phase, input 2).
Step 2. Send the commands listed in Table 13-27 to the relay to setup a test of the response time of
the 87 restrained elements.
Table 13-27. Restrained Element Response Time Setup Commands
Command Purpose
A= Gain access
SL-N=NONE Zero out custom logic settings/overwrite with logic =
none settings
Y Confirm overwrite
SL-N=DIFF Sets DIFF as custom logic name
SL-87=1,0 Enables 87
SL-VO1=87RT Enables OUT1 to close with 87 restrained trip
SG-CT1=1,WYE,NA,0 ctr=1, ct=wye, xfmr=na, no grd source
SG-CT2=1,WYE,NA,0 ctr=1, ct=wye, xfmr=na, no grd source
SG-TRIGGER=87RT,87RPU,0 Enable 87RT to log and trigger fault recording
S#-TAP87=MANUAL,2.00,2.00 set tap 1=2.00 and tap 2=2.00
S#-87=0.35,15,0,0,0,1 Minpu = 0.35, slope = 15%, 2
nd
= disabled, 5
th
=
disabled, URO= disabled, 2
nd
harm sharing = shared
E Exit
Y Save settings
Step 3. Apply 1 multiple of tap current (2 amperes) to both A-phase input 1 and A-phase input 2 (at
180
o
phase relation to input 1).
Step 4. To force a restrained trip at 1.5 times pickup, you must apply a step change in the current on
input 2 to 3.05 amps. Apply the step change in current to input 2 and record the time interval
between the time the step change was initiated to the time OUT1 output contact closes (the
restrained trip (87RT)).
Step 5. Reduce the current to input 2 until OUT1 contact opens.