Question

c) Figure Q1c represents the magnetic circuit of a primitive relay. The core having mean circumference length '$l_e$' of 360 mm. The air gap lengths are 1.5 mm each. The density of 0.8 T is required to actuate the relay. The magnetization curve for this core is given in Table 1. Neglect the magnetic leakage and fringing effect; i. Determine the current '$i$' in the coil. [9 marks] ii. Compute the values of core's permeability '$\mu$' and relative permeability '$\mu_r$'. [4 marks] iii. If the air gap is zero, find the current in the coil for the same flux density (0.8 T) in the core. [4 marks] B (Tesla) 0.4 0.5 0.6 0.7 0.8 0.9 1.0 H (At/m) 290 350 400 450 510 580 700 Table 1 N Core Mean path Figure Q1c: Magnetic circuit of primitive relay [Total: 25 marks]

          c) Figure Q1c represents the magnetic circuit of a primitive relay. The core having
mean circumference length '$l_e$' of 360 mm. The air gap lengths are 1.5 mm each.
The density of 0.8 T is required to actuate the relay. The magnetization curve for
this core is given in Table 1. Neglect the magnetic leakage and fringing effect;
i.
Determine the current '$i$' in the coil.
[9 marks]
ii.
Compute the values of core's permeability '$\mu$' and relative permeability '$\mu_r$'.
[4 marks]
iii. If the air gap is zero, find the current in the coil for the same flux density
(0.8 T) in the core.
[4 marks]
B (Tesla)
0.4
0.5
0.6
0.7
0.8
0.9
1.0
H (At/m)
290
350
400
450
510
580
700
Table 1
N
Core
Mean
path
Figure Q1c: Magnetic circuit of primitive relay
[Total: 25 marks]

c) Figure Q1c represents the magnetic circuit of a primitive relay. The core having
mean circumference length 'le' of 360 mm. The air gap lengths are 1.5 mm each.
The density of 0.8 T is required to actuate the relay. The magnetization curve for
this core is given in Table 1. Neglect the magnetic leakage and fringing effect;
i.
Determine the current 'i' in the coil.
[9 marks]
ii.
Compute the values of core's permeability 'μ' and relative permeability ''.
[4 marks]
iii. If the air gap is zero, find the current in the coil for the same flux density
(0.8 T) in the core.
[4 marks]
B (Tesla)
0.4
0.5
0.6
0.7
0.8
0.9
1.0
H (At/m)
290
350
400
450
510
580
700
Table 1
N
Core
Mean
path
Figure Q1c: Magnetic circuit of primitive relay
[Total: 25 marks]

Added by Brenda G.

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