ABB CA-26 Instrukcja obsługi - Strona 9

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Figure 13: Percentage Slope Curve of the CA-16 and CA-

26 Relays with Six Restraint Windings in

Series.

125 or 250 Vdc WL relay switch or equivalent, use

the 0.2 ampere tap; for 48 Vdc applications set relay

in 2 tap and use WL relay coil style number 304-

C209G01 or equivalent.

5.3.

Indicating Instantaneous Trip (IIT)

Since the minimum and maximum markings on the

scale only indicate the working range. The core

screw must me adjusted to the value of pick-up

desired. The application of IIT unit is intended to get

faster operating speed for heavy internal faults. For

bus protection, it is recommended the IIT unit be set

higher than 50% of the maximum external fault cur-

rent contributed from the bus and with all circuits in

service. For transformer protection, apply IIT unit

where internal fault current can exceed twice the

Courtesy of NationalSwitchgear.com

maximum total current flowing through the differential

zone for a symmetrical external fault. Set IIT unit at

50% external fault current or higher than transformer

inrush current depending on which is greater.

6. INSTALLATION

The relays should be mounted on a switchboard

panel or their equivalent in a location free from dirt,

moisture, excessive vibration, and heat. Mount the

relay vertically by means of the four mounting holes

on the flange for semi-flush mounting or by means of

the rear mounting stud or studs for projection mount-

ing. Either a mounting stud or the mounting screws

may be utilized for grounding the relay. The electrical

connections may be made directly to the terminals by

means of screws for steel panel mounting or to the

terminal studs furnished with the relay for thick panel

mounting. The terminal studs may be easily removed

or inserted by locking two nuts on the stud and then

turning the proper nut with a wrench.

For detailed FT case information, refer to I.L. 41-076.

7. ADJUSTMENTS AND MAINTENANCE

Sub 2

849A343

The proper adjustments to insure correct operation of

this relay have been made at the factory. Upon

receipt of the relay, no customer adjustments other

than those covered under "SETTINGS" should be

required.

7.1.

Acceptance Check

The following check is recommended to insure that

the relay is in proper working order.

A. Minimum Trip Current

Apply current to terminals 12 and 13 of the relay.

The relay should operate as follows:

1. CA-16

2. CA-26

B. Percentage Differential Characteristic

Apply 16 amperes to terminals 9 and 19 of the

41-337.3L

0.15 amperes ± 5%

1.25 amperes ± 5%