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Doc. no. : HTML-S_Kor_2016, Rev. 0
Issued date : 2016. 11
HITROL Co., Ltd
1. Introduction
This document describes the operating principles of HTML-S, which is a thermal
dispersion-type level switch; the procedures for its installation, operation, and
maintenance; and the procedures for troubleshooting. This level switch is designed to
detect and output existence/inexistence of fluid, which is output to the contact point of
a relay.
2. Operating Principles
This level switch utilizes two types of RTD sensors, namely reference RTD and active
RTD, for measuring fluid levels. The reference RTD sensor measures the fluid
temperature, while the active RTD sensor having a hot-wire measures temperatures
higher than the fluid temperature. When the level of the measured fluid is detected by
the level element, the temperature of the active RTD changes because the caloric value
of the heater is transferred to the measured fluid through the area where the level
element contacts the measured fluid. At this time, △T, the difference in the measured
temperatures between the reference RTD and the active RTD, is formed. Then, the level
transmitter determines if fluid is detected based on the △R of the RTD sensors with
regard to △T, and outputs the contact point of the relay.
3. Specifications
3.1
Input power voltage: 110–130 VAC, 50–60 Hz, ±10%, 10 W maximum.
3.2
Number of sensor lines: 1
3.3
Measurable fluid: Liquid
3.4
Measurement method: Thermal dispersion–type
3.5
Depth of the level measuring sensor insertion: Variable depending on the pipe size
(user specifiable)
3.6
Operating pressure: Max 10 bar (higher pressure available upon user’s request)
3.7
Operating temperature:
−
40℃ to +75℃
3.8
Response time: 1–100 sec (user specifiable)
3.9
Output signal: Relay 1 DPDT
3.10
Capacity of output contact point: 5 A 30 VDC, 5 A 250 VAC
