CHAPTER 3 REPAIR OF HIGH VOLTAGE SECTION

CHAPTER 3

REPAIR OF HIGH VOLTAGE SECTION

Section I. HIGH VOLTAGE CABINET

3-1. General

seals or replace damaged one, tighten loose hardware or

The high voltage cabinet is a weatherproof housing with

replace any that is missing. Replace broken

two hinged front panels (upper and lower), two removable

or cracked insulating barriers and cable supports.

rear panels (upper and lower), and a transition area. The

cabinet houses the load break switch in upper front

3-3. Inspect and Replace Lightning Arresters

section, three lightning arrestors and a heater in lower

a. Inspect.

front section. The rear panels allow access for connecting

the primary conductors up and through the bottom to the

CAUTION

connectors on rear of load break switch. The transition

Lightning arresters are live equipment. No

area provides a housing for the connections to the

work should be done or contact made with

primary sides of the transformer from load break switch,

them while the line is energized. (Current

with access panels front anti rear. All panels are secured

flows through an arrester from line to

with hex head bolts. The front upper panel allows for a

ground. A potential gradient exists that is

visual inspection through two non-reflecting windows,

hazardous if handled while energized.

and operation of switch with panel closed. The switch

operating handle socket is covered and has a lockable bar

(11)

Inspect insulator for damage caused by

to prevent unauthorized switching.

external flashover. If cracked or burned, replace.

(12)

Inspect for damage to apparatus protected

3-2. Enclosure Inspection and Repair

by or near arrestor.

a. Inspect exterior and interior for dents, holes,

b. Replace. Refer to figure 2-13.

scratches, bends. panel alignment, weather seals

CAUTION

and other damages.

Make sure lines are de-energized, and load

b. Inspect interior for loose or missing hardware,

breaker switch and main circuit breaker are

broken or cracked cable supports or insulating

open.

barriers.

(1) Remove line connection at top of arrester.

c. Straighten dents and bends, fill holes, clean,

(2) Remove ground connection on bottom of arrester.

prime and repaint bare metal, cement loose weather

(3) Loosen nut of clamp holding arrestor, and remove

arrestor.

(4) Replace or install in reverse order.

Section II. LOAD BREAK SWITCH

auxiliary blade. When the switch is opened the

3-4. Load Break Switch Inspection and Repair

auxiliary blades contacts are the last to part and will

a. Description. The load break switch is a

initiate all arc in the chute. The hot arc releases gases

manually operated, triple pole disconnecting switch with

from the last plastic chute in such volume that the arc is

an integral interrupter that has the capability of

blown away from the rapidly moving auxiliary blade and

interrupting transformer magnetizing and load current

cooled by contact with the larger area of tine chute sides.

within its rating. It has a manually charged, spring stored

After the arc has been extinguished, the blade will

energy operating mechanism capable of closing the

continue to open producing a sufficient air gall to

switch against maximum rated short circuited current.

isolate the termiillali

The operation of the switch is accomplished by manual

rotation of the detachable operating handle through an arc

(b) Switch Inspection Refer to TM 5-6120-250-12.

of 180 The switch has a positive closing and opening

1 2.

operation supplied from the stored energy of springs. The

(c) Switch Repair Refer to Checks and Adjustment

interrupting ability of the switch is accomplished by the

paragraph 2-14b.

use of an arc chute type interrupter and an

3-1