87
Voltage but no current (open circuit) Current cannot flow because the
switch is open and the circuit is broken. The lamp is not glowing. No voltage
and no current (open circuit, no voltage source) Current cannot flow because
without the cell there is no source of voltage. The lamp is not glowing.
Put the sentences in each part in a correct order. Entitle each part.
Translate into Russian
1.
a)
In general, a switch consists of a mechanical device, such as a circuit
breaker, or a solid-state device, such as a transistor, Schottky diode, or field-
effect transistor.
b)
It is a device that causes the operating conditions of a circuit to change
between discrete specified levels.
c)
It selects from two or more components, parts, or circuits the desired
element for a particular mode of operation.
d)
A switch is a device that opens or closes a circuit.
2.
a)
A circuit breaker is a device such as a contactor, switch, or tripping
device that is used to make or break a circuit under normal or fault conditions.
b)
An unwanted arc is often produced as the circuit breaker operates and this
can be minimized using magnetic blow out device.
c)
This device is fitted to the circuit breaker and produces a magnetic field in
the neighbourhood of the arc, thus causing the path length of the arc to increase
and thereby extinguishing it rapidly.
d)
When used for fault conditions an automatic break and manual make
system is commonly used.
3.
a)
The frequency and voltage at which a fuse is designed to operate are
specified by the fuse frequency rating and fuse voltage rating.
b)
The fuse characteristic is the relation between the current through the fuse
and the time taken for the fuse to operate
c)
A fuse consists of a short length of easily fusible wire that is used to
protect electric circuits or devices by melting (“blowing”) at a specific current
and thus breaking the circuit.
d)
The fuse current rating is the maximum value of the current that the fuse
will conduct without melting.
