Basler BE1-CDS220, Instruction Manual, Page: 349 / 476

BE1-CDS220 Testing And Maintenance 13-35
Sidebar 13-4. Maximum Restraint When Decreasing One Input from Balance
A second way to test the restrained pickup of the BE1-CDS relay is to decrease one of two currents,
initially applied in balance, to create an imbalance. In this narrative, input 2 current will be the input
deviated. A similar analysis can be made for deviating input 1 current.
By decreasing the input current I
2
from balance, the value of I
2trip
is defined as:
I
2trip
= I
2balance
(1- (
100
slope
)) in per unit Sidebar 13-4, Equation 1
with the minimum trip point established as:
I
2trip min
= I
2balance
– minpu in per unit Sidebar 13-4, Equation 2
where: minpu is the minimum pickup setting.
Under test and in-service conditions, the following equations determine whether the relay operates along
the flat minimum pickup or the slope of the operating characteristic. If:
I
restraint at balance
> (minpu/(
100
slope
) in per unit, use Equation 1, or, if
I
restraint at balance
< (minpu/(
100
slope
) in per unit, use Equation 2.
With the maximum restraint operating principle of the BE1-CDS relay, as one input current is decreased
from balance, the other input current, remaining the greater of the two currents, will be the restraint current
(in per unit). Since that current remains fixed while the other is decreased, the operate current plotted
against the restraint current will be a vertical line on the operating characteristic diagram.
If you are applying this relay using the maximum restraint operating characteristic, continue with Step 4.
Otherwise, you may proceed directly to Step 12 to test the average restraint operating characteristic.
Step 4. Send the commands listed in Table 13-19 to the relay.
Table 13-19. Setup Commands
Command Purpose
A= Gain access
S#-87=0.35,15,0,0,0,1 minpu=0.35,slope=15%,2
nd
=dis,5
th
=dis,URO=dis,
2
nd
harm sharing=1 (yes)
E Exit
Y Save settings
Step 5. Apply balancing current to phase A, input 1 and phase A, input 2 at the magnitude indicated in
the first row of either Table 13-20 (5 ampere sensing) or 13-21 (1 ampere sensing) and slowly
increase input 1 until OUT1 closes. Reference the appropriate table to verify pickup accuracy.
Step 6. Repeat for all values and (optionally) reconnect to phases B and C, inputs 1 and 2 when
advancing through the set of test values in the table. It is not necessary to test each phase at
all the values listed to verify the response of each phase. If your relay is supplied with the HMI
option, navigate to the \PROT\SGn\87\87 screen to make the listed slope setting changes.
Notice that the test values in Tables 13-20 and 13-21 are intended to show operation on both the minimum
operate and slope portion of the operating curve.
Step 7. Verify that pickup occurred within the specified accuracy of the relay. Accuracy when
increasing or decreasing the input current is
±
4% of setting or 75 milliamperes (whichever is
larger) for 5 ampere sensing inputs and
±
4% of setting or 25 milliamperes (whichever is larger)
for 1 ampere sensing inputs.