4
VM1/A/P
- INSTALLATION AND SERVICE INSTRUCTIONS ANSI: ... 15 KV; ... 2000 A; ... 31.5 K A
—
1. Foreword
1.3 Drawout
A Drawout circuit breaker is a breaker that may be
removed from a cell without unbolting connections
or mounting supports. It is intended for use in ABB
PowerCube modules. It contains primary and
secondary disconnects and provides two operating
positions: Disconnect and Connect.
1.4. Information on this booklet
This booklet provides information for the VM1/A/P
circuit breakers as described below. Not all sections
of the bulletin apply to all types of VM1/A/P circuit
breakers. For example, the racking and interlock
sections do not apply to the fixed mount breaker
styles. All information in this booklet was current at
the time of printing. Unless otherwise noted, all
references in this booklet are determined by
viewing the circuit breaker from the front.
The purpose of this manual is to provide
instructions for unpacking, storage, installation,
operation, and maintenance for VM1/A/P vacuum
circuit breakers. This manual should be carefully
read and used as a guide during installation, initial
operation, and maintenance.
The specific ratings of each model circuit breaker
are listed on the individual nameplates. The VM1/
A/P circuit breakers are protective devices. As such,
they are maximum rated devices. In no event should
they be applied outside of their nameplate ratings.
1.5. Principle of extinction of the
vacuum interrupter
Given the relatively low static pressure of the
interruption chamber (between 10-4 and 10-8 hPa),
a relatively limited distance between the contacts is
required to obtain high dielectric strength. The
vacuum arc is extinguished on the first passage of
the current through natural zero.
Considering the limited distance between the
contacts, the high conductivity of the plasma of
metallic vapours, the drop in voltage of the arc and,
moreover, the short arcing time, the energy
associated with the arc is extremely limited,
therefore producing benefits for the useful life of
the contacts obtained and, consequently, for the
useful life of the vacuum interrupters.
1.6. Application of the X-ray
emission Standards
One of the physical properties of vacuum insulation is
the possibility of X-ray emission when the interrupter
contacts are open.
The specific tests carried out at the PTB laboratories
(Physikalisch-Technische Bundesanstalt, in Brunswick
- Germany) show that local emission at a distance of
10 cm from the interrupter or pole surface, does not
exceed 1 mSv/h.
It follows that:
•
at the rated service voltage the use of vacuum
interrupters is absolutely safe;
•
application of the withstand voltage at industrial
frequency, according to the IEC 62271-100, VDE 0670
and IEEE C37.04 Standards, is safe;
•
application of a voltage higher than the withstand
voltage at industrial frequency or of a direct current
test voltage in direct current, specified in the IEC,
VDE and ANSI/IEEE Standards, cannot be used;
• limitation of the above-mentioned local
phenomena, with interrupters with open contacts,
depends on keeping the specified distance between
the contacts.
This condition is intrinsically guaranteed by correct
operation of the operating mechanism and by
adjustments of the transmission system.
Summary of Contents for VM1/A/P
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Page 51: ...MEDIUM VOLTAGE PRODUCTS 51 51 ...
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