GE Industrial Solutions Power-Vac ML-20 Mechanism - Manual (Page 4)

4
PowerVac ® Vacuum Circuit Breaker
with ML-20 Mechanism
SECTION 1—Introduction
This manual provides the information needed by the user to
properly install, operate and maintain the ML-20 PowerVac ®
Breaker.
The PowerVac ® vacuum breaker is a horizontal drawout
interrupting element for use in metalclad switchgear to provide
protection and control of electrical apparatus and power systems.
To the extent required applicable ANSI, IEEE and NEMA Standards
are met. No such assurances are given with respect to local
codes and ordinances, as they vary greatly.
1.1—Safety
Each user must maintain a safety program for the protection of
personnel, as well as other equipment, from the potential hazards
associated with electrical equipment.
The following requirements are intended to augment the user's
safety program, but NOT supplant the user's responsibility for
devising a complete safety program. The following basic industry
practiced safety requirements are applicable to all major electrical
equipment such as switchgear or switchboards. GE neither
condones nor assumes any responsibility for practices which
deviate from the following:
1. ALL CONDUCTORS MUST BE ASSUMED TO BE ENERGIZED
UNLESS THEIR POTENTIAL HAS BEEN MEASURED AS
GROUND AND ADEQUATE CAPACITY GROUNDING
ASSEMBLIES HAVE BEEN APPLIED TO PREVENT
ENERGIZING. Many accidents have been caused by
unplanned energization from non-recognized back feeds,
equipment malfunctions, and from a wide variety of sources.
2. It is strongly recommended that all equipment be completely
de-energized, verified to be “dead”, then grounded with
adequate capacity grounding assemblies prior to any
maintenance. The grounding cable assemblies must be able
to withstand energizing fault levels so that protective
equipment may clear the circuit safely. Additional discussion
on this concept is covered in Chapter 20 of ANSI/NFPA 70B,
Electrical Equipment Maintenance.
3. Although interlocks to reduce some of the risks are provided,
the individual's actions while performing service or
maintenance are essential to prevent accidents. Each person's
knowledge; mental awareness; and planned and executed
actions often determine if an accident will occur. The most
important method of avoiding accidents is for all associated
personnel to carefully apply a thorough under-standing of the
specific equipment from the viewpoints of its purpose, its
construction, its operation and the situations which could be
hazardous.
All personnel associated with installation, operation and
maintenance of electrical equipment, such as power circuit
breakers and other power handling equipment, must be
thoroughly instructed, with periodic retraining, regarding power
equipment in general as well as the particular model of
equipment with which they are working.
Instruction books, actual devices and appropriate safety and
maintenance practices such as OSHA publications, National
Electric Safety Code (ANSI C2), National Electric Code, and
National Fire Protection Association (NFPA) 70B Electrical
Equipment Maintenance must be closely studied and followed.
During actual work, supervision should audit practices to assure
conformance.
1.2—Maintenance
Excellent maintenance is essential for reliability and safety of any
electrical equipment. Maintenance programs must be tuned to
the specific application, well planned and carried out consistent
with both industry experience and manufacturer's
recommendations. Local environment must always be considered
in such programs, including such variables as ambient
temperatures, extreme moisture, number of operations, corrosive
atmosphere or major insect problems and any other unusual or
abusive condition of the application. One of the critical service
activities, sometimes neglected, involves the calibration of various
control devices. These monitored conditions in the primary and
secondary circuits, sometimes initiating emergency corrective
action such as opening or closing circuit breakers. In view of the
vital role of these devices, it is important that a periodic test
program be followed. As was outlined above, it is recognized that
the interval between periodic checks will vary depending upon
environment, the type of device and the user's experience.
It is the GE recommendation that, until the user has accumulated
enough experience to select a test interval better suited to the
individual requirements, all significant calibrations be checked at
an interval of one to two years.
To accomplish this, some devices can be adequately tested using
test sets. Specific calibration instructions on particular devices
typically are provided by supplied instruction books.
Instruction books supplied by manufacturers address components
that would normally require service or maintenance during the
useful life of the equipment. However, they can not include every
possible part that could under adverse environments.
Maintenance personnel must be alert to deterioration of any part
of the supplied switchgear, taking actions, as necessary to restore
it to serviceable status.
Industry publications of recommended maintenance practices
such as ANSI/NFPA 70B, Electrical Equipment Maintenance,
should be carefully studied and applied in each user's formation of
planned maintenance.
Some users may require additional assistance from GE in the
planning and performance of maintenance. Local GE Sales can be
contracted to either undertake maintenance or to provide
technical assistance such as the latest publications.
The performance and safety of all equipment may be
compromised by the modification of supplied parts or their
replacement by non-identical substitutes. All such design changes
must be qualified to the original manufacturers specifications.
The user should methodically keep written maintenance records
as an aid in future service planning and equipment reliability
improvement. Unusual experiences should be promptly
communicated to GE.