5196106426

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oco <	• 0	*•	2	1	*	1	4	7	•	4	10	OCO C
			tM{4MC(l(CliIC VOl			IAOC 14	AilOtUTf	Mltl!VOtVS
• o	o.ooo	0.014	0.0 74	0.119	0.114	0.199	0.2)4	0.277	0.117	0.1)7	0.147	0
10	0.14T	0.41T	0.*7T	0.1)7	0.117	0.197	0.4)7	0.477	0.714	0.7)4	0.744	10
20	0.T44	0.414	0.4 74	0.4)4	0.440	1.000	1.0*1	1.041	1.122	1.142	1.20)	20
10	1.201	1.24*	).291	1.121	1.144	l.*OT	1 .**•	1 • * • 4	1.129	1.170	1.411	)o
*0	1.411	1.412	1.491	1.71*	1.774	1.417	l.ili	1.49*	1.4*0	1.941	2.022	*0
10	2.022	2.044	2.101	2.1*0	2.144	2.22*	2.270	2.112	2.1)1	2.17*	2.4)6	10
40	2.414	2.4TT	2.114	2.140	2.401	2.4*1	2 •* 9*	2.724	2.7*7	2.407	2*9)0	60
?0	2.410	2.4*2	2.411	2.471	1.014	1.014	1.100	1.1*1	1 • ) 9 1	1.22*	1.264	70
• 0	1.244	1.10T	1.144	1.140	1.412	)•* 7)	)•)!)	1.104	1.144	1.4)7	1.441	• 0
*0	1.44)	1.722	1.7*4	1.401	1.4*7	1.444	1.4)0	1.471	*•012	6.0)4	4.04)	40
100	*•041	4.117	4.174	4.214	*•24)	*•102	*.)*)	* • )•*	*•*24	*•*47	*•104	100
110	4.104	4.166	4.190	4.412	*•*71	*•71*	4.711	*.74*	*.i)7	6.474	4.414	110
120	4.4)4	4.440	1.001	1.0*2	1.04)	1.12*	1.14*	1.20)	1.2*4	1.747	1.127	120
110	*1.12 T	1.149	1.404	l.*10	1.490	1.1)1	1.171	1.612	1.4)2	1.47)	1.7)1	DO
1*0	1. TH	1 • TT*	1.414	1.411	1.441	1.4)*	1.47*	4.014	4.0)7	4.047	4.1)7	1*0
1)0	4.11T	4.ITT	0.214	4.214	4.294	4.1)4	4.174	*•*14	4.4)9	4.444	6.1)4	1)0
140	4.114	6.1T4	4.4)9	4.019	4.494	4.7)4	4.774	4.419	4.4)9	6.444	4.4)4	160
1 TO	4.414	4.4T4	T.014	7.017	7.044	7.1)9	7.174	7.214	7.2)4	7.244	7.1)4	170
liO	T.114	T.1T4	7.419	7.414	7.644	7.1)4	7.174	7.414	7.4)9	7.647	7.7)7	1 ®0
140	T.T1T	T.TTT	T.41T	7.417	7.4)7	7.4)7	7.477	4.017	4.0)7	• .047	4.1)7	HO
200	4.117	• .ITT	9.2)4	4.214	4.244	4.1)4	4.17*	9 •* 1 *	• .*)*	4.477	4.1)7	200
210	4.11T	4.ITT	4.4)7	4.417	4.497	4.7)7	4.777	4.417	4.4)7	• .47*	• • 4 )•	210
2*0	4.414	4.4T4	9.0)4	4.Oli	9.044	4.1)4	4.174	4.220	9.2*0	7.100	4.1*1	220
210	4.141	4.141	9.*2I	f .*42	4.102	4.1*1	4.14)	4.*2*	4.***	4.7oi	4. 7*1	2)0
2*0	4.T41	4. Ti*	9.424	4.447	4.407	4.4*4	4.94*	10.029	10.070	lo.ui	10. Dl	2*0
210	10.111	10.142	10.211	10.27*	10.111	I0.111	10 • )*4	10.*17	10.*74	10.)17	10.160	2)0
240	10.140	10.400	10.4*1	10.442	10.721	10.7**	10.401	10.4*4	10.447	10.72*	10.464	2*0
2 TO	10.444	11.010	11.011	11.091	11.11*	11.171	11.214	11.2)7	11.299	11.1)7	11.141	270
240	11.141	U.*22	11 • *4 1	11.10*	11.1*4	11.147	11.424	11.444	11.711	11.7)2	11.74)	240
240	U.T41	11.411	11.974	11.914	11.41*	12.000	12.0*2	12.04)	12.12)	12.1*4	12.207	240
100	12.20T	12.2*4	12.240	12.112	12.171	12 •* 11	12.41*	12.644	12.1)4	12.141	12.47)	100
110	12.421	12.44*	12.704	12.7*7	12.7i*	12.4)1	12.472	12.41*	12.4)1	12.777	11.0)4	l&O
120	11.014	11.040	11.122	11.14*	11.201	11.2*7	11.24*	li.lll	11.172	11.41*	I1.414	120
110	11.*14	ll.*4T	11.119	11.14)	11.421	)).**)	l).704	11.7*4	11.740	1)••17	11.47*	1)0
140	11••T*	11.411	T1.41T	11.444	1 * .0* 1	1* .04)	14.121	14.1*7	14.204	1 *•2)0	16.242	1*0
110	1*.242	14.11*	1* .17*	)*.*)•	l*.*40	1*•102	1*•1**	l*.)44	l*.*2i	1 * • 4 7o	16.7)2	1)0
140	14.T12	1*.Tl*	)*.70*	14.414	)*.490	14.422	1*.4**	11.004	11.0*4	11.070	11.1)2	1*0 •
1T0	11.112	11.IT*	11.214	11.214	11.100	11.1*2	11.14*	1)•*2*	11.449	11.110	11.112	170
140	11.112	11.14*	11.414	11.474	11.72)	11.7*1	11.40	11.4*7	11.444	l).7)|	11.47*	1*0
140	11.47*	14.014	14.014	10.100	14.1*2	14.19*	14.227	10.249	14.1)1	14.1)1	14.14)	140
*00	14.141	l4.*14	14.440	14.122	14•14*	14.407	14.4*4	14.09)	14.7)1	14.77*	14.414	*00
4)0	14.414	14.440	14.402	10.4*1	14.4*7	17.024	17.072	17.11*	17.1)6	17.144	17.2*1	*10
420	IT.241	IT.241	17.124	17.1*0	17.*|0	17.*1)	17.**!	17.5)7	17.540	17.422	17.64*	*20
410	i T.444	1T.70T	17.744	17.742	17.4)*	17.47*	17.*1*	17.4*1	14.00*	14.0**	14.044	*10
440	19.04•	14.11)	li.171	14.210	14.214	li.10)	14.1*1	14.145	|i.*24	li.*70	14.11)	**o
410	14.1)1	li.lll	. 1 i. 144	14.0*0	14.491	14.721	14.7*4	14.410	14.95)	14.94)	14.4)4	*)o
440	14.414	14.940	19.021	14.041	14.104	14.1*0	14.1*)	14.2)1	14.274	14.120	19.16)	4 60
4 TO	14.141	19.401	19.449	14.440	14.1)1	14.174	)4.*14	19.461	19.70)	14.76*	14.744	*70
440	14.T44	19.411	14.471	14.41*	14.414	20.001	70.0**	20.044	20.127	20.172	20.21*	* *0
440	20.214	20.21T	20.244	20.1*2	20.141	20.*27	20.670	20.112	20.55)	20.144	20.4*0	*40
100	20.440	20.441	20. m	20.744	20.4)1	20.41)	20.4*4	20.4)4	20.441	21.02*	21.046	100
110	21.046	21.109	21.112	21.14*	21.2)7	21.240	21.122	21.16)	21.407	21.4)0	21.44)	110
120	21.441	21.111	21.174	21*421	21.44)	21.704	21.7*4	21.741	21.0*	21.47*	21.4)4	120
110	21.414	21.4*2	22.00*	22*0*7	72.040	22.1)2	22.17)	22.214	22.240	27.10)	22.146	1)0
1*0	22.1*4	22.144	22.*11	22.471	22.114	22.1)4	22.401	22.66*	22.4*7	22.774	22-772	1*0
110	22.TT2	22.011	22.417	22.400	22.4*2	22.441	21.024	21.070	21.11)	21.1)4	21.144	1)0
140	21.149	21.241	21.244	21*124	21.144	21.411	2).*)*	21•*47	21.1)4	21.142	21.42*	160
1T0	21.42*	21•4* T	21.7)0	21.712	21.741	21.4)7	21.440	21.42)	21.4*1	2*.004	2*.0)0	170
140	24.010	2*.041	2*.I14	2* • 1 Ti	2*.221	24.2*1	2*.)06	2*.)*i	24.141	24.41*	24.*74	140
140	2*.4T4	24.114	2*.141	24.40*		2*. 444	2*.7)|	2*.77*	2*.417	2*.i)4	2*.4o2	140
4 00	24.402	24.44*	24.947	21.024	21.072	21.116	21.1)7	21.144	•21.2*2	21.24*	21.127	600
410	21.12T	21.1*4	21.*12	21.*1*	21.*47	21.1)4	21.142	21.42*	21.4*4	2).*04	21.7)1	4 lO
420	21.TH	21.T4*	21.41*	21.474	21.421	21.4**	24.004	24.0*4	24.091	24.1)1	24.174	620
410	24.1T#	24.214	24.240	24.101	24.1*1	24.147	24.6)0	24.672	24.11)	24.1)7	24.144	6)0
440	24.144	24.442	20.44*	24.724	24.7*4	24.411	24.45)	24.44*	24.4)4	24.960	27.022	6*0
410	2T.022	2T.041	27.107	27.)**	27.1*2	27.21*	27.274	27.114	27.)*1	27.*0)	27.**)	6)0
440	2T.441	27.667	27.124	27.172	27.*)*	27.414	TT.***	27.7*0	27.74)	27.42)	27.4*7	6*0
4 TO	2T.46T	2 T.404	27.41)	27.441	24.0)1	24.074	24.120	24.1*2	24.20*	24.7*4	24.244	4 70
490	2«.244	24.110	24.172	24*41*	2l.*14	24.4*4	24.5*0	24.14)	24.*2)	24.447	24.704	440
440	24.T04	24.711	24.741	29.411	74.477	24.41*	21.4*1	24.002	27.0**	24.044	24.126	6 40
TOO	24.124	24.|TO	29.2)2	24.21*	24.2*4	24.1)4	24.140	29.422	24.*** *	24.10)	29.1*7	700
TIO	24.1*T	24.14*	29.411	24.671	24.711	24.714	24.744	24.4*0	24.442	24.92*	29.96)	710
T20	20.441	10.00T	10.0*4	10*041	10.1)2	10.17*	10.214	10.2)7	10.244	10.1*1	10.14)	720
T10	10.141	10.42*	10.44*	10.104	10.1*9	10.1*1	)0.*)2	)0.6 7*	10.71*	10.7)7	10.794	7)0
T*0	)0.Tt4	10.4*0	10.442	10.42*	10.441	11.007	11.0*4	11.090	)&.!)!	11.17)	11.21*	7*0*
TIO	11.21*	11.214	11.2*7	11.11*	11.190	11.422	)!•**)	1).10*	)!.)**	1I.147	11.*24	7)0
T40	11.424	11.4T0	11.7)2	71.711	11.74*	11.4)4	11.977	11.914	11.9*0	12.001	12.0*2	7*0
TTo	12.042	12.04*	12.121	12.144	12.207	)2.2*4	12.240	12.1)1	)2.)72	12.41*	12.4)1	770
740	12.411	12.**4	12.117	12.174	12.419	12.4*1	12.7C2	12.7*1	12.74*	12.425	12.46*	790
T40	12.444	12.40?	12.944	12.4*0	11.0)1	11.072	11.11)	)).!)*	11•14)	11.2)4	11.277	790
• 00	11.2TT	11.Ili	11.114	ll.*00	11.4*1	)).**2	)).!2)	)).)**	11.40*	11•**5	11 • 646	400
410	11#* ® 4	11.727	11.7*i	11.404	11.910	11.441	11.4)1	11.472	)*.0I)	)*•05*	14.04)	4)0
420	1*.041	1*.1)4	1* • 1 7*	14.217	)*.2l4	)*.24*	1* • 1 )4	)*.)40	16.421	1*•*41	14.102	620
410	14.102	u.1*1	!*•!•!	1*.42*	1*•441	14.701	1* . 7*i	1*•74 7	14.477	1*••* •	14.404	4)0
• 40	14.404	14.449	14.440	11.010	11.071	11.111	11.1)2	)).|4*	11.21)	11.771	11.114	4*0
410	11.11*	11.11*	11.141	11.*11	11.* 76	11.114	D.llT	11.147	)).*)7	11.474	11.7)4	4)0
440	11.Tli	11.714	11.744	11.414	11.440	11.420	11.4*0	14.000	16.0*1	14.041	16.121	960
4 TO	14.121	14.142	14.202	14.2*2	)4.2*7	14.12)	)4.)*)	14.60)	)*•**)	)4.4i)	16.12*	4 70
4 40	14.12*	14.14*	14.*0*	14.4**	14.49*	14.72*	14.74*	)*.40*	)*••**	14.44)	16.42)	640
4 40	14.421	14.441	17.001	17.0*1	17.041	17.12)	17.1*1	11.20)	17.2*1	17.76)	17.12)	640
400	IT.121	17.1*1	17.*01	17.4*1	17.*4*	17.12*	17.1*6	17.60*	17.***	17.64*	17.72*	400
410	1T.T2*	1T.7**	17.401	17.46)	17.44)	)7.*2)	17.46)	14.002	14.0*2	li.042	16.122	410
420	li.122	14.142	li.20)	14.24I	14.291	14.120	>i.)*0	>4.*00	14.6)4	14.474	14.119	420
410	14.114	14.114	14.1*4	14.414	14.*77	)i • 71 7	14.756	14.946	14.41*	16.41)	14.415	4)0
4*0	li.411	14.41*	14.44*	)4.0)1	14.07)	14.112	14.152	19.141	14.2)1	14.210	19.110	4*0
410	14.110	14.1**	14.144	19.*24	1*.*47	14.107	)4.!**	)V.)i)	)4.*2)	19.66*	14. 70)	41o
440	14. »0!	)4.T*|	14.74 2	14.921	)4.i*|	14.400	)4.*)9	14.4)9	*0.019	*0.0)9	*0.04*	9*0
4 TO	*0.0*4	-0.11*	*0.)»1	*0.21*	*0.21)	*0.242	*0.1)2	*0.17)	.0.610	*0.449	* 0 • * • •	9 ?0
440 a a	*0.*44	*0.121	*0.1**	*0.401	*0.6*1	*o.*t*	*0.72)	*0.’*2	*0.401	*0.4*0	*0.679	940
440	*0.4T4	*0•4|i	*0.417	*0.4*6	*1.0)1	*1.07*	*1.11)	*1.1)2	61.191	*1.2)0	*1.249	940

TABLE 2: Seebeck Voltage vs Temperaturę (°C) for a type K Thermocouple (Chromet/Alumel)

90

German physicist Thomas Johann Sce-beck, who found that a smali electric current was gencrated in a Circuit formed from two different metals, pro-vided that one of the two junctions be-tween the metals was raised to a higher temperaturę than the othcr junction.

It turned out that the current was produced by an elcctromotive force, sińce dubbed the Seebeck EMF, whose voltage is roughly proportional to the temperaturę differencc between the two junctions.

METAL B

Fig.1: In its most basie form, a thermocouple consists of a Circuit madę from two metals. When one junction is madę hotter than the other, a current flows.

The basie idea is shown in Fig.l. In reality there are two different Seebeck voltages gencrated, one at each junction and with opposing polarities, with the voltage produced by the hotter junction greater than that produced by the cold junction. The resultant voltagc is therc-fore the difference between the two.

By the way, weTe talking about quite smali voltagcs here — typically only a few tens of millivolts. The actual vo!t-age levcl depends on the two metals used to make the junctions. A number of different metal combinations have been used over the years, for thermo-couples designed for different applica-tions. The main types used are shown in Table 1. Each combination of metals givcs a different relationship between temperaturę and Seebeck output volt-age, and has features which make it suitable for different kinds of use.

Notę especially the type N thermo-couplc, which is the most recent type to be dcveloped and largely supersedes many of the earlier types. It uses Nickel-Chromium-Silicon alloy (“Nicro-sil”) and Nickel-Silicon-Magnesium. alloy (“Nisil”), which give exccllent temperaturę stability and long working life at temperatures up to about 1230°C. It also has considerably higher output than the precious metal types S and R, and is also much lower in cost.

The type N thermocouple becamc an international standard type in 1984, after its development by Australian scientist Dr Noel Burley.

ELECTRONICS Australia. September 1987