Transcript AVOP-ELEKTRO-SMI-001

Tutorial: Mechanic - electrician
Topic:
Basics of electrical engineering
the 2nd. Year
The measuring system1
Prepared by: Ing. Jiří Smílek
Projekt Anglicky v odborných předmětech, CZ.1.07/1.3.09/04.0002
je spolufinancován Evropským sociálním fondem a státním rozpočtem České republiky.
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System with a rotating magnet
Construction:
In the hollow coil is a pivotally
positioned magnet.
Attached to the shaft are a needle
and spring, which are used for
power supply and also holds a
pointer to zero .
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Principal function:
An electric current passes
through the stationary coil
creating an electric current.
A permanent magnet makes
it so that it’s induction curve
undergoes the same sense
as the induction curve of
magnetic field coils.
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Features:
◦ Measure the DC voltage and current,
◦ Little accuracy
◦ Sensitive to external magnetic field;
◦ Advantage:
 Simplicity.
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Application:
◦ The electrical equipment of motor vehicles
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Electro-magnetic system – with a rotating coil
Construction:
In the cavity between the magnetic
pole attachments is a magnetic
coil pivotally placed in an
aluminum frame.
Attached to the shaft are a needle
and spring, which are used for
power supply and also holds a
pointer to zero.
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Principal function:
Passing a current through the coil creates a
magnetic field, which tries to turn the coil so that
the direction of the magnetic flux coincides with
the direction of the magnetic flux of the
permanent magnet.
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Properties:
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Measure the DC voltage and current,
The scale is linear,
Magnetic damping (eddy currents in an aluminum roller)
High accuracy (0,1 and 0,2%),
Low self consumption (8 - 3 W),
Sensitivity of the gross mechanical and electrical usage,
Strong influence of temperature
Application:
◦ DC voltmeters and ammeters and indirectly for the measurement
of other variables.
Electro-magnetic systems
types of devices
Electro-magnetic device – with a rotating coil
• measurement of DC voltage and current
Electro-magnetic ratiometric device
• measurement of resistance
Electro-magnetic device with a built in insulated
thermocouple
• measurement of non-sinusoidal currents
Electro-magnetic device with an integrated regulator
• measurement of sinusoidal alternating currents
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Name the well-known measuring systems
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Describe the construction 1. system
Describe the principal function 1. system
Draw the type of measuring device 1. system
Name the application of the system 1. system
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Describe the construction 2. system
Describe the principal function 2. system
Draw the type of measuring device 2. system
Name the application of the system 2. system
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Mužík, J. Management ve vzdělávání dospělých. Praha: EUROLEX BOHEMIA, 2000. ISBN
80-7361-269-7.
Operační program Vzdělávání pro konkurenceschopnost, ESF 2007 – 2013.
Available at: http://www.msmt.cz/eu/provadeci-dokument-k-op-vzdelavani-prokonkurenceschopnost
Electrical Measurement textbooks– Ing. Pavel Vylegala, SŠE Ostrava, 2006
Electrical Measurement textbooks– SNTL, 1981