- 品牌/商標:P+F
- 企業(yè)類型:貿(mào)易商
- 新舊程度:全新
- 原產(chǎn)地:P+F
在設(shè)計電阻溫度計3 -
4線連接,這是必要的,以確保供應(yīng)
電纜敷設(shè)的測量電阻器,這是不
情況下,所有的溫度計。往往是由連接
在這種結(jié)構(gòu)中的連接頭。這,
再次產(chǎn)生問題的,導(dǎo)線的電阻和
隨溫度變化的影響s以上的長度的
實際溫度計。由于比較小
連接頭之間的距離和測量
電阻,這些錯誤是遠遠小于與2線連接。
如果一個電導(dǎo)體的溫度下在
Continuous correction of the line resistance during
measurement is not possible. That is why the supply cables
should not be longer than about 100 m (109.36 yd) in the
case of the 2-wire connection. The resistance of a 1 m
(1.09 yd) long copper cable with a cross section of 1 mm2 is
approx. 0.017 Ω. Consequently, in this case, a wire resistance
of about 1.7 Ω is likely. Changes to resistance due to the
infl uence of temperature are included in the result. If the
cable lengths are greater, so that higher wire resistances are
unavoidable, you should use 3- or 4-wire connections.
3-Wire Connection
In order to measure the line resistance RL and its changes,
a third wire is laid directly to the connector point at the
measurement resistor. The wire resistance of this line has no
infl uence on measurement because the supply current does
not pass through it. Thus, the voltage is measured directly on
the measurement resistor.
梯度,電子流內(nèi)發(fā)生
導(dǎo)體,造成電動勢
(EMC)的溫度成比例
漸變。的量和方向,這
電動勢依賴于溫度的大小
梯度和導(dǎo)體材料上
(圖38) 。兩個自由端之間測得的電壓
導(dǎo)體產(chǎn)生的電壓差異,取決于
的溫度差異和熱電
導(dǎo)體的特性。這種現(xiàn)象,被稱為
塞貝克效應(yīng),由TJ塞貝克發(fā)現(xiàn)