pwz data sheet zener barrier the zener barrier is a safety barrier for operating an electronic instrumentation system as an intrinsically safe explosion-proof system in processes subjected to explosive gases or vapor. various types are available for transmitter, electro-pneumatic final controlling element, thermocouple and resistance bulb, and can be combined with the field in- strument mounted in a hazardous area to operate the measur- ing instrument as an intrinsically safe explosion proof system. features 1. high safety explosion-proof zener barrier ? this barrier has been designed according to the latest ex- plosion-proofing principles and it complies with the in- spection standards of the research institute of industrial safety, ministry of labor, of the japanese government. iec recommendations and vde standards have been taken into due consideration in design and manufacture. ? the voltage limiter circuit (zener diode) and thick film fuse are fully incorporated, and the voltage limiter circuit is trip- licated. thus, safety and reliability of the system have been improved by far. ? the thick film fuse offers a high safety maintenance rating of 550v ac. ? the hybrid ic circuit forms a small and compact system, and meets the creeping distance and other standard val- ues. the system can be easily mounted on the instru- ment panel. cable connections and separation of both in- trinsically safe and non-intrinsically safe circuits is as- sured. ? in order to prevent handling error, various failproof devices. (such as bright blue indication of intrinsically safe termi- nals, use of contact prevention cover, doubling of bus bar mounting screws, asymmetric design, color identification according to models, etc.) are incorporated. ? the classification of hazardous areas (division 0) and group- ing of explosive gases (i3ng5) are wider than with other explosion-proof structures. 2. high reliability barrier ? the structure and circuits are simple with fewer parts than an insulation barrier or repeater amplifier barrier, and fea- ture high reliability. ? since all processes from product development to manufac- turing are performed by intracompany techniques and fa- cilities, system quality is fully guaranteed with adoption of reliable design techniques such as fmeca, etc., complete manufacturing and testing facilities, manufacturing quality control system, etc. ? the manufacturing techniques, manufacturing test facili- ties, and quality control system for thick film fuse and hy- brid ic have been inspected and approved by the industrial safety institute of the japanese government. ? the system also assures high reliability with the use of strictly selected parts high derating design, reduced sol- dering due to use of a hybrid ic, deterioration resistance by thick film fuse, improved vibration resistance, etc. 3. improved system design ? since the safety maintenance rating is as high as 550vac, receiving instruments can be optionally selected and the system easily can be connected to a computer control sys- tem. ? various types of barrier assemblies are prepared and easily selected according to the measuring instruments com- bined. ? since this system uses a small-sized relaying terminal board structure, the instrument panel can be easily de- signed and connected. date EDS13-9F oct. 20, 1989
pwz 2 4. maintenance and checks facilitated ? check terminals are provided for checks on doubled cur- rent limiting circuit functions. specifications explosion-proofing specifications type of explosion-protection and grouping of explosive gases: intrinsic safety jis i3ng5 (i3ag5 for zla, zlc) (i3ag5 used for electro-pneumatic final con- trolling element and i3ag4 for multi-point temperature converter.) max. safety rating: 550v ac and 340v dc installation: zener barrier is fastened by two m4 screws onto copper bus bar in a non-hazardous area. class 1 (10 ? or less) bus bar grounding is required. measuring instrument combined: the measuring instrument to be connected to the intrinsically safe circuit is subject to inspection. (see table 1). (the same in- spection certificate as there for the zener barrier should be attached without fail) the measuring instruments on the non-in- trinsically safe circuit, are not subject to in- spection, and those having a voltage of less than max. safety rating can be optionally connected. ambient temperature of combined measuring instrument: the transmitter and electro-pneumatic final controlling element installed in the hazard- ous area must be used at an ambient tem- perature lower than the following; modification of combined measuring instrument: the combined measuring instrument in- stalled in the hazardous area cannot be modified. (unit exchange is possible). wiring lc: use within inspection conditions (see table 2). general specifications ambient temperature: -10 to 50 ; storage temperature: -25 to 85 ; ambient humidity: less than 90%rh optional accuracy: better than 0.1% external dimensions (h w d): 30 70 55mm mass {weight}: approx. 250g case: glass fiber resin case(black) terminals: connected by crimp terminals with m4 screws and insulation sleeve. terminals on intrinsically safe explosion- proof circuit side are indicated in bright blue. cover: transparent plastic cover for protection of terminals operating conditions for measurement: circuit resistance, circuit voltage, common mode, etc. are limited. (see table 2) table 1. types and ,code symbols for combined measuring instru ments and inspection certificate number instrument ambient temperature fc transmitter 60 c or less electro-pneumatic final controlling element 60 c or less multi-point temperature converter 60 c or less abgriff transmitter 50 c or less type for trans- mitter (4 to 20ma, 2-wire system) pwzb10a1 fc transmitter*1 field indicator bule 30745 ffi multi- point temperature converter pwzb11a1 multi-point temperature converter (frl) + pt resistance bulb bule 42150 for thermo- couple pwzb30a1 thermometer (fta, ftb, ftc, ftd) red 20983 for resist- ance bulb (3-wire system) pwzb4 a1 thermometer (ftf) orange 20984 for contact input *4 notes: *1 excluding emf transmitter (fra) and flow transmitter (fjq). fc transmitter modification no. is type 2. *2 electro-pneumatic converter modification no. is type 4. *3 positioner modification no. is type 5. *4 for contacts located in a hazadous area, an inspection certificate prate must be attached to a contact not equipped with a power supply. also, when an acetylene atmosphere exsts in a hasardous area, ensure contacts do not include bare copper or copper alloy. on the receiving signal side of the zener barrier, it is necessary to use an exclusive intrinsically safe auxiliary relay (pwr). contact*4 21857 for electro- pneumatic final control element (4 to 20ma, 2-wire system) pwzb20a1 electro-pneumatic converter *2 posisioner *3 green 41022 multi-point temperature converter (frl) + thermocouple 42151 abgriff transmitter, field indicator 29077 code symbols combined measuring instruments color idemti- fication inspection certificate no.
3 operating principles the zener barrier consists of three safety maintenance elements: (i) current limiter circuit, (ii) voltage limiter cir- cuit, and (iii) fuse for voltage limiter circuit protection. wiring resistance of each element increases during nor- mal operation, and does not affect any measurement. the current limiter circuit is an intrinsically safe circuit which limits the current to an intrinsically safe level even if a short-circuit, ground, or other fault occurs. the voltage limiter circuit suppresses the voltage to less than the zener voltage to maintain the intrinsically safe functions even if a dangerous voltage exceeding the working voltage value or less than the rated max. safety voltage is applied to the nonintrinsically safe circuit due to a fault. system composition diagram the fuse protects the zener diode from self-heating and burn out thus losing its voltage limiting function. cut-off time tf of the fuse and fusing time tz of the zener diode are in cooperation with each other as described below. tz > 10tf the zener barrier consists of a circuit containing three safety maintenance elements sealed in a case having a relaying terminal board structure. the intrinsically safe circuit terminals and the nonintrinsically safe circuit terminals are isolated from each other so that they are not shorted to one another thus losing their functions. the grounding terminal is grounded to the bus bar which is also grounded with a sufficiently low grounding resistance. the zener barrier includes four barriers according to applications. the current limiter circuit generally uses resistors. part of the 4 to 20ma current limiter circuit consists of a hybrid ic doubled to enhance its reliability. the voltage limiter circuit consisting of a zener diode or ordinary diode is triplicated to assure safety and reliability. the newly developed thick film fuse has a high safety rating of 550v ac or 340v dc, and resists vibrations and deterioration by corrosion. it features high reliability from the viewpoint of explosion-proofing and measurement. remarks: (1) the intrinsically safe circuit must satisfy the conditions for explosion-proofing given in table 2. (2) refer to the separate manual for intrinsically safe explosion-proof wiring and work inside the instrument panel.
pwz 4 table 2 operating conditions for measurement and explosion-proofing code symbols pwzb10a1 model item intrinsically safe terminal 2, 4 2, 4 2, 4 2, 4 2, 4, 6 1, 3 1, 3 1, 3 1, 3 1, 3, 5 terminal no. rated working voltage 25.8v 0.5 dc (across 1 and 7, 8) total resistance value 175 ? /20ma (across 1 and 2) 129 ? 4.5 ? (across 3 and 4) 175 ? /20ma (across 1 and 2) 129 ? 4.5 ? (across 3 and 4) 449 ? 14.5 ? (across 1 and 2, 3 and 4) 59 ? 2.5 ? (across 1 and 2, 3 and 4, 5 and 6 ) 175 ? /20ma (across 1 and 2) 89 ? 3.5 ? (across 3 and 4) 14v dc or less (across 1 and 3) 0.4v dc or less (across 1 and 3, 1 and 5, 3 and 5) 14v dc or less (across 1 and 3) 25.8v 0.5 dc (across 1 and 7, 8) working con- ditions for measurement remarks remarks (1) the reference for wiring distance differs according to the type of explosive gases, ambient conditions, presence o r absence of shield, wiring diameter, etc. the above table gives values with regard to i3ng5. consult fuji if there is any question. (2) the maximum allowable common mode voltage depends on the charateristies of the voltage regulating circuit. be careful not to exceed this value. working con- ditions for explosion- proofing non-intrinsically safe terminal grounding terminal check terminal 7, 8 6 max allowable external wiring resistance max allowable external wiring capacitance 0.022 f or less 1mh or less max allowable external wiring inductance* * only one field indicator (fxg) or one transmitter with built-in indicator can be used. when the field indicator is used ployed, internal resistance of 12 ? should be subtracted, * only one posi- tioner or con- verter (zla, zlc) can be employed. cws (1.25mm 2 ) 125m reference for wiring distance according to working conitions (approx. distance) cevs (1.25mm 2 ) 250m cevs (1.25mm 2 ) 500m cevs (1.25mm 2 ) 250m cevs (1.25mm 2 ) 220m cws (1.25mm 2 ) 250m 100m, although this depends upon compensating conductors. 2.5km with contact input 2.5km cws (1.25mm 2 ) 125m cws (1.25mm 2 ) 110m 0.09 f or less 0.5mh or less not limited not limited 0.022 f or less 1mh or less 0.25 f or less 5mh or less 0.22 f or less 1mh or less 52 ? by receiving instrument (approx. 100 ? ) by receiving instrument (approx. 50 ? /wire) 40 ? 52 ? max allowable common mode voltage 0.5v ac rms max. safety rating 550v ac 340v dc 550v ac 340v dc 550v ac 340v dc 550v ac 340v dc 550v ac 340v dc 10v ac rms 0.1v ac rms 0.5v ac rms 0.5v ac rms 7, 8 6 7, 8 6 7, 8 7, 8 fc transmitter pwzb11a1 pwzb20a1 pwzb30a1 pwzb40a1 abgriff transmitter w pz 1 2 1 345678 description classification for transmitter (4 to 20ma, 2-wire system) for ffi multi-point temprature converter for electro-pneumatic final controlling element (4 to 20ma, 2-wire system) for thermocouple, contact input for resistance bulb (100 c or more) and st transmitter for resistance bulb ( 50 c or more and 100 c or less) b10 b11 b20 b30 b40 b42 a
5 connections diagrams 1. zener barrier for transmitter (pwzb10a1) 2. zener barrier for electro-pneumatic converter and positioner (pwzb20a1) 3. zener barrier for thermocouple (pwzb30a1) 4. zener barrier for contact input (pwzb30a1) 5. zener barrier for resistance bulb and st input (pwzb40a1) 6. zener barrier for ffi multi-point temperature converter (pwzb11a1)
pwz outline diagram (unit : mm) note: asterisked (*)items: non standard. scope of delivery zener barrier related devices combined measuring instruments ordering information 1. product name 2. code symbols information in this catalog is subject to change without notice. printed in japan head office gate city ohsaki, east tower, 11-2, osaki 1-chome, shinagawa-ku, tokyo 141-0032, japan http://www.fesys.co.jp/eng instrumentation div. international sales dept. no.1, fuji-machi, hino-city, tokyo, 191-8502 japan phone: 81-42-585-6201, 6202 fax: 81-42-585-6187 http://www.fic-net.jp/eng caution on safety *before using this product, be sure to read its instruction manual in advance.
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