ABB CA-26 Manuale di istruzioni - Pagina 7
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Figure 10: External Schematic of the Type CA-26 Relay for Transformer Protection and Bus Protection.
4.5.
ENERGY REQUIREMENTS
Burden of each restraint coil at 5 amperes
VOLT AMPERES
.75
Continuous Rating
1 second rating
Burden of Operating Circuit
VOLT AMPERES
Variable (see Figure 7)
Continuous rating 8 amperes
1 second rating 280 amperes
Courtesy of NationalSwitchgear.com
4.6.
4.6.1. CA-16
To determine the ac connections, identify each pri-
POWER FACTOR
mary circuit as either a "source" or "feeder". As
defined here, a feeder contributes only a small por-
.7
tion of the total fault-current contribution for a bus
14 amperes
fault. Next lump a number of feeders into a "feeder
group" by paralleling feeder ct's, taking the precau-
460 amperes
tion that each feeder group has less than 14 amperes
load current (restraint coil continuous rating). If the
bus reduces to more than four circuits, parallel ct's
until only four circuits remain. Then connect these
ct's to the relays per Figure 8.
The four circuit bus arrangement of Figure 8 must be
used with caution. Tripping speed is dependent on
the net torque (operating minus restraint) applied to
the two induction discs. Restraint torque is zero if the
contribution from each of the four circuits is equal
and the operating time of the relay is as described by
Figure 6. On the other hand, restraint torque is
CONNECTIONS
41-337.3L
Sub 3
606B269
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