Instruction manual

KRB-5377

6-2-6. Shunt trip device (SHT)

The following describes how to replace the shunt trip device(SHT).

1) Make preparations for parts replacement. Refer to section 6-2-1.

2) Turn the cover mounting screws five or six turns to loosen as shown in Fig. 69. If the ACB is equipped with side covers, first

remove the side covers and then loosen the front cover mounting screws. (The cover mounting screws are of captive type and

cannot be removed from the side and front covers.)

3) Pulling the charging handle down, remove the front cover.

4) Remove the contact block fixing screws as shown in Fig. 70.

5) Flip the contact block up as shown in Fig. 71.

6) Turn the SHT mounting screws eight or ten turns to loosen, disconnect the manual connector (black), and then remove the SHT.

See Fig. 86.

Fig. 86 Removing the SHT

7) Reinstall each part or component in reverse order of removal after inspection. When installing the SHT, make sure the

nameplate on the SHT can be viewed from the front of the ACB.

z Fig. 87 provides the general view of the SHT.

Fig. 87 General view of SHT

Hand connector (black)

Contact block

SHT mounting screw,

Pan head M4 × 80 (2)

with spring washer

Tightening torque: 1.3 - 1.7 N·m

SHT

LRC

Hand connector (black)

PlungerSHT mounting screw

Moving core

(located in the center hole)

Coil resistance measuring point

Plunger length measurement