MINIATURE THERMOCOUPLE CONNECTOR MARLIN MINI Marlin Manufacturing Corporation 12800 Corporate Drive Cleveland, OH 44130 216-676-1340 800-321-6648 USA 216-676-1344fax sales@marlinmfg.com 2 2 THEORY OF OPERATION APPLICATION: Intended for convenient plug-in connections of thermocouples and thermocouple extensions. Ideal for small diameter MIMS and fine wire. PURPOSE: To maintain the integrity of thermocouple circuits by utilizing proper thermocouple alloys and wiring techniques. Use for thermoelectric circuits consistent with millivolt (mV) requirements per ASTM E 1684. NOT FOR USE IN ELECTRICAL APPLICATIONS AC OR DC. A thermocouple is a pair of dissimilar wires joined as to produce a thermally generated emf when its ends are at different temperatures. Several combinations of dissimilar pairs have become standardized and used in temperature instrumentation. T,J,K,N,R,S,B, are letter codes designating some popular thermocouple materials that are readily available. Each combination has its own unique emf output and metallic properties that make them applicable for a particular use. Thermocouple theory allows the extension of the wires without affecting its emf output when the extension wire and connectors have the same thermoelectric characteristics. For example, when a “K” type thermocouple is being used the wires and connectors used to extend it must be also type “K”. The types have assigned color codes, for instance, “K” type has yellow code for the USA. This code allows for easy identification so as to help prevent mismatching of extension wires, connectors, and thermocouples. For example, if in the yellow color code of the type “K” circuit a blue type “T” connector would be an obvious improper component. The generalized thermocouple system may be divided into five basic areas: Hot-Zone; Gradient Area; Extension Region; Reference Junction; and Readout. The extension region is generally where thermocouple connectors are utilized in order to facilitate thermocouple-to-readout hook-up. In a simplistic and isolated system the thermocouple will perform to specifications. Thermocouple connectors and panels are polarized making them virtually impossible to miss-mate positive and negative thermocouple legs. Wiring a positive-to-negative and then a negative-to-positive down line is called a double reversal and is NOT desirable because it will give false temperature readouts. Marlin’s connectors and panels are molded from glass reinforced thermoset compounds for high strength and dependability. They WILL NOT MELT and are rated for continuous use to 400°F (205° C) and 500°F (260°C) intermittently and high-temp 800°F (425° C) and 1000°F (538°C) intermittently. They are color coded and letter coded for type and polarization identification (high-temp are molded in HTRED only). Current (mV) carrying metal parts are made of alloys matching the characteristics of the T/C type with which they are intended to be used. Contact springs are nonmagnetic, non-corrosive and specially selected and processed to withstand the rated operating conditions. Wire and connections must be of “like” alloys from the hot junction to the readout Thermo elements are joined to form the “hot” junction. Thermocouple Grade wire in working zone. Soft insulation is flexible and durable while providing electrical isolation. Thermocouple Extension grade wire may be used in this area if limits are not exceeded. The “RED” color code always denotes the ”NEGATIVE” element for ASTM (USA) thermocouple wire. See color chart for other designations.
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