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/ je spolufinancován Evropským sociálním fondem a státním rozpočtem České republiky.
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.
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.
Features: ◦ Measure the DC voltage and current, ◦ Little accuracy ◦ Sensitive to external magnetic field; ◦ Advantage : Simplicity. Application: ◦ The electrical equipment of motor vehicles
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.
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.
Properties: ◦ 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 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 Electro-magnetic systems types of devices
Name the well-known measuring systems ◦ 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
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
Mužík, J. Management ve vzdělávání dospělých. Praha: EUROLEX BOHEMIA, ISBN Operační program Vzdělávání pro konkurenceschopnost, ESF 2007 – Available at: konkurenceschopnosthttp:// konkurenceschopnost Electrical Measurement textbooks– Ing. Pavel Vylegala, SŠE Ostrava, 2006 Electrical Measurement textbooks– SNTL, 1981