Coefficients Certificate Value
R(.01) R(273.16K)
aa5
bb5
c0.0
d0.0
a4 a5
b4 b5
7.9.10 IEC751
The IEC751 probe typeis for standard PRTs (RTDs) conforming to the IEC751
or DIN-43760 standards. This typeof probe is generally low cost and has a
wide operating range (–180°Cto 420°C or higher), but has limited accuracy
(0.15°C to 4°C). There are no user programmable coefficientsassociated with
thisprobe type. Temperature is converted from resistance based upon the stan-
dard PRTtable resident in the instrument.
7.9.11 CVD
The CVD (Callendar-VanDusen) type is used with PRTs that have unique cali-
bration coefficientsor do not match the IEC-751 specification. This type of
probe is generallylow cost, has a wide operating range (–180°C to 420°C or
higher), and has moderate accuracy(0.05°C to 1°C). This type uses the
Callendar-VanDusen equation to calculate temperature from resistance:
rt C
Rt tt
R
([ ])°=
+− −
⎛
⎝
⎜⎞
⎠
⎟
⎡
⎣
⎢⎤
⎦
⎥
⎧
⎨
⎩
⎫
⎬
⎭≥
0
0
11
100 100 10αδ
1100 100 1100 1100
3
+− −
⎛
⎝
⎜⎞
⎠
⎟−−
⎛
⎝
⎜⎞
⎠
⎟⎛
⎝
⎜⎞
⎠
⎟
⎡
⎣
⎢
αδ βttt t t
⎢
⎤
⎦
⎥
⎥
⎧
⎨
⎪
⎩
⎪
⎫
⎬
⎪
⎭
⎪<
⎧
⎨
⎪
⎪
⎩
⎪
⎪t0
The coefficientsR0, α,δ,andβcan be set by the user using the functions
“R0", ”Alpha", “Delta”, and “Beta” respectively.When editing “Alpha” there is
an assumed 10–3exponent (i.e. 3.8500 is actually 0.0038500).
7.9.12 YSI-400
The YSI-400 type isfor 2252Ωthermistorsmatching the characteristics of the
YSI-400 series of thermistors.This type of probe generally is low cost, has a
limited operating range (–40°C to150°C), good accuracy (0.1°C to 0.4°C), and
excellentresolution (0.002°C). There are no user programmable coefficients as-
sociated with this probe type. Temperatureis converted from resistance based
upon a standardYSI-400 table resident in the instrument.
43
7 Display Functions
CAL MODE