Fluke 1522 manual

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60

Ir a la página of

Buen manual de instrucciones

Las leyes obligan al vendedor a entregarle al comprador, junto con el producto, el manual de instrucciones Fluke 1522. La falta del manual o facilitar información incorrecta al consumidor constituyen una base de reclamación por no estar de acuerdo el producto con el contrato. Según la ley, está permitido adjuntar un manual de otra forma que no sea en papel, lo cual últimamente es bastante común y los fabricantes nos facilitan un manual gráfico, su versión electrónica Fluke 1522 o vídeos de instrucciones para usuarios. La condición es que tenga una forma legible y entendible.

¿Qué es un manual de instrucciones?

El nombre proviene de la palabra latina “instructio”, es decir, ordenar. Por lo tanto, en un manual Fluke 1522 se puede encontrar la descripción de las etapas de actuación. El propósito de un manual es enseñar, facilitar el encendido o el uso de un dispositivo o la realización de acciones concretas. Un manual de instrucciones también es una fuente de información acerca de un objeto o un servicio, es una pista.

Desafortunadamente pocos usuarios destinan su tiempo a leer manuales Fluke 1522, sin embargo, un buen manual nos permite, no solo conocer una cantidad de funcionalidades adicionales del dispositivo comprado, sino también evitar la mayoría de fallos.

Entonces, ¿qué debe contener el manual de instrucciones perfecto?

Sobre todo, un manual de instrucciones Fluke 1522 debe contener:
- información acerca de las especificaciones técnicas del dispositivo Fluke 1522
- nombre de fabricante y año de fabricación del dispositivo Fluke 1522
- condiciones de uso, configuración y mantenimiento del dispositivo Fluke 1522
- marcas de seguridad y certificados que confirmen su concordancia con determinadas normativas

¿Por qué no leemos los manuales de instrucciones?

Normalmente es por la falta de tiempo y seguridad acerca de las funcionalidades determinadas de los dispositivos comprados. Desafortunadamente la conexión y el encendido de Fluke 1522 no es suficiente. El manual de instrucciones siempre contiene una serie de indicaciones acerca de determinadas funcionalidades, normas de seguridad, consejos de mantenimiento (incluso qué productos usar), fallos eventuales de Fluke 1522 y maneras de solucionar los problemas que puedan ocurrir durante su uso. Al final, en un manual se pueden encontrar los detalles de servicio técnico Fluke en caso de que las soluciones propuestas no hayan funcionado. Actualmente gozan de éxito manuales de instrucciones en forma de animaciones interesantes o vídeo manuales que llegan al usuario mucho mejor que en forma de un folleto. Este tipo de manual ayuda a que el usuario vea el vídeo entero sin saltarse las especificaciones y las descripciones técnicas complicadas de Fluke 1522, como se suele hacer teniendo una versión en papel.

¿Por qué vale la pena leer los manuales de instrucciones?

Sobre todo es en ellos donde encontraremos las respuestas acerca de la construcción, las posibilidades del dispositivo Fluke 1522, el uso de determinados accesorios y una serie de informaciones que permiten aprovechar completamente sus funciones y comodidades.

Tras una compra exitosa de un equipo o un dispositivo, vale la pena dedicar un momento para familiarizarse con cada parte del manual Fluke 1522. Actualmente se preparan y traducen con dedicación, para que no solo sean comprensibles para los usuarios, sino que también cumplan su función básica de información y ayuda.

Índice de manuales de instrucciones

  • Página 1

    1522 Handheld Thermometer Readout User’ s Guide Rev. 5B2202 Hart Scientific[...]

  • Página 2

    Rev. 5B2202 Fluke Corporation, Hart Scientific Division 799 E. Utah Valley Drive • American Fork, UT 84003-9775 • USA Phone: +1.801.763.1600 • Telefax: +1.801.763.1010 E-mail: support@hartscientific.com www.hartscientific.com Subject to change without notice. • Copyright © 2005 • Printed in USA[...]

  • Página 3

    T able of Contents 1 Bef ore Y ou Start . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1 Symbols Used . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 Safety Information . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2.1 W ARNINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2.2 CA UTIONS [...]

  • Página 4

    6.5 Probe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 6.6 INFO-CON Connector . . . . . . . . . . . . . . . . . . . . . . . 29 7 Display Functions . . . . . . . . . . . . . . . . . . . . . . . . . 31 7.1 Blank Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 7.2 Min/Max Mode . . . . . . . . . . . . . . . . . .[...]

  • Página 5

    8.2.1 Primary Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 8.2.2 Calibration Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 9 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 9.1 Required Equipment . . . . . . . . . . . . . . . . . . . . . . . . . 53 9.2 Calibration Procedure[...]

  • Página 6

    iv Figures and T ables T able 1 International Electrical Symbols . . . . . . . . . . . . . . . . . . . . . 1 Figure 1 Front V iew . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Figure 2 T op and Side V iew . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Figure 3 INFO-CON Connector . . . . . . . . . . . . . . . . . . .[...]

  • Página 7

    1 Bef ore Y ou Start 1.1 Symbols Used T able 1 lists the International Electri cal Symbols. Some or all of these symbols may be used on the instrument or in this manu al. Symbol Description AC ( Alternating Current) AC- DC Batter y CE Complies with European Uni on Directiv es DC Double Insulated Electric Shock Fuse PE Ground Hot Surf ace (Bur n Haz[...]

  • Página 8

    Symbol Description Canadian Standards Associati on O VERV OL T AGE (Installat ion) CA TEGORY II, P ollution Degr ee 2 per IEC1010-1 re - f ers to the le vel of Impulse Wit hstand V oltage protect ion provided. Equipment of O VERV OL T AGE CA TEGOR Y II is energy-consuming equipment to be suppli ed from the fix ed installat ion. Examples include hou[...]

  • Página 9

    • The A C adapter has circuits with high voltage inside that could present danger of electrical shock or fire if exposed. If the A C adapter is damaged in any way or becomes hot, discontinue its use immediately , disconnect it from any A C supply , and hav e it replaced. Do not attempt to open, repair, or continue using a damaged or defective A C[...]

  • Página 10

    • Keep the probe wires clean and aw ay from fluids. 1.3 A uthoriz ed Service Centers Please contact one of the follo wing authorized Service Centers to coordinate service on your Hart product: Fluke Corporation, Hart Scientif ic Division 799 E. Utah V alle y Driv e American Fork, UT 84003-9775 USA Phone: +1.801.763.1600 T elefax: +1.801.763.1010 [...]

  • Página 11

    Fluke South East Asia Pte Ltd. Fluke ASEAN Regional Of fice Service Center 60 Alexandra T errace #03-16 The Comtech (Lobby D) 118502 SINGAPORE Phone: +65 6799-5588 T elefax: +65 6799-5588 E-mail: antng@singa.fluke.com When contacting these Service Cente rs for support, please hav e the follo wing information av ailable: • Model Number • Serial [...]

  • Página 12

    2 Intr oduction The Hart 1522 is a low-cost, high-accura c y digital thermometer readout de - signed to be used with PR Ts and thermistors. The unique combination of fea - tures makes this instrument suitable fo r a wide v ariety of application s in industry . Features and capabilities of the 1522 include the following: • Accepts input from plati[...]

  • Página 13

    3 Specifications and En vir onmental Conditions 3.1 Specifications Resistance Range 0 Ω to 500 k Ω Resistance Accuracy, PRT, one year † 0 Ω to 25 Ω : 0.002 Ω 25 Ω to 400 Ω : 0.008% (80 ppm) of reading Resistance Accuracy, thermistor, one year † 0 Ω t o2k Ω :0 . 4 Ω 2k Ω to 200 k Ω : 0.02% (200 ppm) of reading 200 k Ω to 500 k Ω : [...]

  • Página 14

    Digital Filter Exponential with adj ustable time constant (1 to 60 seconds) Remote Communications RS-232 s erial, infrared Display LCD, 6-digit x 7-segment wi th 16-character alphanumeric Operating Temperatur e Range 0 to 40°C (32 to 104°F) absol ute 15 to 35°C (59 to 95°F) f ull accuracy Power 12 VDC (AC adapter included) Rechargeable NiMH bat[...]

  • Página 15

    This warrant y extends onl y to the original purchaser and shall not apply to an y product which, in Hart’ s sole opinion, has been subject to misuse, al teration, abuse or abnormal c onditions of operation or handling. Software is w arranted to operate in accordance with its programmed instruc - tions on appropriate Hart products. It is not w ar[...]

  • Página 16

    4 Quic k Start This section briefly explains the basics of setting up and operating your ther - mometer readout. 4.1 Unpac king Carefully unpack the 1522 and accessories and inspect them to make sure all components are present and in satisf actory condition. V erify that the following items are present: • 1522 Thermometer Readout • A C Adapter [...]

  • Página 17

    4.4 Connect the Probe The PR T or thermistor probe connects to the top of the 1522 using Hart’ s unique INFO-CON probe connector . The probe connector is inserted into the top of the instrument wi th the ridged to the back and f its snugly and locked into place when it is fully inserted. The INFO-CON probe connector includes a memory de vice that[...]

  • Página 18

    want to measure the te mperature. DO NO T f orce the probe or otherwi se allo w it to be bent, stressed, or o verheat ed. It can be easily damaged if misused. F or further suggestions on handl ing the probe and using the 1522 and probe to measure temperature accurately , see Section 6.5. For information on the various modes of operation of the 1522[...]

  • Página 19

    5 P ar ts and Contr ols The functions of the v arious features of the 1522 are described below . 5.1 Fr ont View The front of the 1522 features the LCD display and control b uttons. 17 5 Parts and Controls Front View Figure 1 Front Vie w[...]

  • Página 20

    Display -The display sho ws the current temperature (or resist ance) measure - ment on the large numeri c upper portion of the display . It can also show a v ari - ety of information on the small er alphanumeric lo wer portion such as minimum, maximum, delta(x), an d other instru ment settings. Po wer and Backlight button -This b utton turns the in[...]

  • Página 21

    5.2 T op and Side View The top and side of the 1522 feature the probe connector , DC power input, se - rial port, and infrared windo w . Probe Connector - At the t op of the thermometer readout is the opening where the probe connector is inserted. The probe must be connected using an INFO-CON probe connector to measure temperature (see Section 6.6)[...]

  • Página 22

    5.3 Bac k View See Figure 5 on page 25. Stand - The stand at the back of the 1522 can be fl ipped down t o prop up the instrument for better viewing. Battery Compartment - Behind the stand is the compartment that contains the battery pack. The battery pack can be accessed if necessary by opening the bat - tery cove r with a small Philips screwdriv [...]

  • Página 23

    5.5 Accessories The 1522's accessories and their features are described here. AC A d a p t e r - The A C adapter recharges the internal battery pack and may also be used to supply po wer to operate the 1522 whi le the battery i s being charged (see Section 6.2). Serial Cable - The serial cable is used to connect a computer or a printer to the [...]

  • Página 24

    Ordering Infor mation Model Type Range Size Cal Uncertainty and Repeatability † Typical Drift † (1 year) 5613 Pt-100 Ohm, 4-wir e –200 to 300°C 3/16” x 6” (4.76 x 152 mm) ±0.025°C ±0.01°C 5612 Pt-100 Ohm, 4-wir e –200 to 450°C 3/16” x 9” (4.76 x 229 mm) ±0.025°C ±0.01°C 5627–6 Pt-100 Ohm, 4-wir e –200 to 300°C 3/16”[...]

  • Página 25

    computer and written to a file quickly . These items must be p urchased sepa - rately . Log Wa r e Softwar e -T h eL o g Wa r e software are data acquisition software packages that can be used with your t hermometer to collect and graph data. T he software also allo ws the user to download data logged from the instrument's memory to a computer[...]

  • Página 26

    6 General Operation This section e xplains the details of the operat ion of the 1522 with its compo - nents and accessories. 6.1 Battery The 1522 has a b uilt-in nickel-metal-hydride battery pack that can po wer the instrument for about 18 hours before needing to be rechar ged. The battery di s - charges much more quickly if t he display backlight [...]

  • Página 27

    tery automaticall y when it’ s fully char ged. It normally tak es about four hours to fully charge the battery . The instrumen t can be operated while the battery is b e - ing charged. CA UTION: DO NOT leave the A C adapter plugged in for more than 24 consecutive hours or , the battery life could be degr aded. The battery pack can be used for a m[...]

  • Página 28

    adapter supp lied by Hart Scientific. The DC power source plugs in to the DC power i nput on the right side of the 1522. W ARNING: The AC adapter contains high voltage cir cuits that could pr esent danger of electric shock or f ire if e xposed. If the A C adapter is damaged in any way or becomes hot, discontinue its use immediately , dis- connect i[...]

  • Página 29

    second. The display unit associ ated with the measurement is sho wn in smaller type to the right of the measurement. The possible dis play units are degrees Celsius (C), resistance in oh ms ( Ω ), de grees Fa hrenheit (F), Ke lvin (K), and degrees Rankine (R). The display units can be easily changed accessing the Units mode (see Section 7.6 ). The[...]

  • Página 30

    T emperature is generally sensed at the tip of the probe. T o get an accurate tem - perature measurement the probe sheath should be well immersed, with ade - quate depth and fit, into the mediu m to be measured. CA UTION : Pr obes are fr agile devices that can be easily damaged by me - chanical shock, o verheating, and absorption of moisture or flu[...]

  • Página 31

    C1 and P1 terminals and the other single wire to t he C2 and P2 terminals (which are shorted toget her). 1522 Handheld Thermometer Readout User’s Guide 30 GND P1 C2 P2 C1 J1 J2 Hart Scientific Four-wire Connection GND P1 C2 P2 C1 J1 J2 Hart Scientific Three-wire Connection GND P1 C2 P2 C1 J1 J2 Hart Scientific T wo-wire Connection Shor t Shor t F[...]

  • Página 32

    7 Displa y Functions The insturment operates in an y of sev eral modes which determine what infor - mation is visible in th e lo w er alphanumeric portion of the disp lay . The MODE button sequences through the menu functions. This b utton can be pressed re - peatedly until a desired mode is set. Th e v ario us modes are listed below in the order t[...]

  • Página 33

    Each of these operating mod es is described in the sections that follo w . 7.1 Blank Mode This mode is identified by “Blank” that temporarily app ears on the display . 1522 Handheld Thermometer Readout User’s Guide 32 Blank Mode Set Units Min/Max Mode Set Rate Set Resolution Cal Mode Demand Logging button button button button button button (3[...]

  • Página 34

    In this mode nothing appears on the alphanumeric porti on of the display . Use this mode if you are only interested in the latest measurements and want to sim - plify the appearance of the display . The message “Prb cal expired”, “M tr cal expired”, “ Recharge Needed”, or “Probe is locked” may be displayed. 7.2 Min/Max Mode This mod[...]

  • Página 35

    The labels can be pre-loaded using the W indo ws® HyperT erminal or o ther se - rial communications program and the command LBnn[=nnnnnnnn] as de - scribed in Section 8.2.1. The label s can also be pre-loaded using the serial port or the 2374 IR dongle with the 9934 Log Wa r e or 9935 Log Wa r e II software av ailab le by calling an Authorized Ser[...]

  • Página 36

    7.4.1 Clear A utolog? This function clears t he memory of all autologged dat a. Once the 1522 has logged 10,000 readings, further automati c logging is pre vented until the mem - ory has been cleared. Pressing the CLR button cancels the “Clr Autolog?” function and adv ances to the ne x t function. Pressing t he ENT button also ad - vances t o t[...]

  • Página 37

    Press the ENT butt on to stop autologgi ng and to adv ance to the ne xt function. 7.4.5 Dump Data? This function allo ws the user to download t he autologged data using the seri al port or print the do wnloaded dats to a serial printer . T o download using the se - rial port, see Section 8 of this guide before selecting “Y es” when prompted by [...]

  • Página 38

    button stores the selection. If th e MODE b utton or CLR button is pressed with - out pressing ENT the unit remains unchanged. Once the unit is select ed, subse - quent measurements will appear in that unit. After the Min/ Max and Delta(x) modes are initiated, their values are automatically con verted when changing units between °C, K, °F , or R.[...]

  • Página 39

    When editing any parameter , be sure to press the ENT b utton through the enti re line of alphanumeric characters to ensure that the edi ts are stored. Pressing any button other than the ENT button adv ances to the next function wit hout storing the new v alue. If a probe parameter is edited, the ne w parameter value i s uploaded into the INFO-CON [...]

  • Página 40

    b4 [ITS-90 only] - Set the b4 or b5 probe coef ficient R(0) [CVD only] - Set the R0 probe coefficient Alpha [CVD only] - Set the alpha probe coefficient Delta [CVD only] - Set the delta probe coefficient Beta [CVD only] - Set the beta probe coefficient b0 [Therm only] - Set the b0 probe coefficient b1 [Therm only] - Set the b1 probe coefficient b2 [...]

  • Página 41

    pressed, the message “In valid Passcode” i s displayed and the instrument is re - turned to the display mod e that follows the function that was acti ve when the CAL Mode was ent ered. Each indi vidual instrument has its o w n unique passcode. The passcode number is gi ve n on a notice pro vided with this i nstrument. The equipment manager is r[...]

  • Página 42

    7.9.8 Prb T ype This function specif ies the type of probe an d its characterization. It allows the instrument to use the appropriate al gorithm to calculate te mperature from the measured resistance of the probe. The functions that follo w the probe conv er - sion function for settin g probe characterization coeff icients depend on the se - lected[...]

  • Página 43

    Coefficien ts Cer tificate V alu e R(.01) Rtpw a a5, a6, a7, a8, a9, a10, or a11 b b5, b6, b7, b8 or b9 cc 6 o r c 7 dd a4 a4 or a5 b4 b4 or b5 Consider the follo wing e xamples. Example 1: A PR T was calibrated to ITS-90 and its calibration certificate states v alues for coeff icients R(273.16K), a4, b4, a8, and b8. Set the instrument's coef [...]

  • Página 44

    Coefficien ts Certificate Va lue R(.01) R(273.16K) aa 5 bb 5 c0 . 0 d0 . 0 a4 a5 b4 b5 7.9.10 IEC751 The IEC751 probe type is for standard PR Ts (R TDs) conforming to the IEC751 or DIN-43760 standards. This type of probe is generally lo w cost and has a wide operating range (–180°C to 420°C or higher), b ut has limited accurac y (0.15°C to 4°[...]

  • Página 45

    7.9.13 THERM The THERM type is for th ermistors that hav e u nique calibration coeff icients or do not match the YSI-400 speci ficati on. This type of probe general ly has mod - erate cost, a limited operating range (–40°C to 150°C), excellent accurac y (0.005°C to 0.01°C) and e xcellent resol ution (0.002°C). This type uses the Steinhart-Ha[...]

  • Página 46

    measurement error due to the resistance of the wires. W ith four wires the in - strument can completely cancel the error . The internal measurement circuit is configured di fferentl y depending on the number of wires. Note: The instrument tries to calculate a measurement e ven if the wire settings are incorrect. Therefore, the Probe Wires setting m[...]

  • Página 47

    each date segment and the ENT b utton to move to the ne xt date segment on the right. Press ENT when the date is correctly entered. Press CLR to move to the next funct ion without changing the date. 7.9.19 MDue This function sh o ws the date the instrument is du e for calibration and allows it to be set. The meter calibration due date is regularly [...]

  • Página 48

    8 Comm unications Interface Remote communications allows an e x ternal de vice, such as a computer, to com - municate with the i nstrument to obtain measurement data and control its opera - tion. Communication is accomplished with v arious commands issued to the instrument through the RS-232 serial port. 8.1 RS-232 Connection The three-conductor ja[...]

  • Página 49

    The protocol for serial communicatio ns is 8 data bits, 1 stop bit, and no parity . Use no flow contr ol. The baud rate is f ixed at 2400, the linefeed to ON (all car - riage returns are follo wed by a linefeed (ASCII decimal 10)), and the duple x to HALF disabling ech o. The serial port can be used to transmit measurements to a computer or pri nte[...]

  • Página 50

    Description Command Example Response Format Response Example Range Set autolog mode on/off . Note: Exit Autolog menu to use this command. Aft er alog =ON is sent, the but tons are disabled until t he command alog=OFF is sent. alog=[ON/OFF] alog=ON ON or OFF Clear autolog memory aclr aclr Initiate downl oad of autologged data. Note: Read Section 11.[...]

  • Página 51

    Description Command Example Response Format Response Example Range n Numeric data supplied by user 9 Numeric data retur ned to user x Character data r eturned to user 8.2.2 Calibration Commands The following group of commands directly or indirectly af fect the accurac y of the instrument. These c ommands should only be used by qualif ied, authorize[...]

  • Página 52

    Description Command Example Response Format Response Example Range Read probe wires w[ires] wi wi: 9 wi: 4 Set probe wire s w[ires]= 2/3/4 wi=4 2,3,4 Read probe calibrati on date pc[al] pcal pc: yyyy-mm-dd pc: 1999-03-28 Set probe calibrat ion date pc[al]=yyyy-mm-dd pc=1999-03-28 1971-01-01 to 2099-12-31 Read probe due date pd[ue] pdue pd: yyyy-mm-[...]

  • Página 53

    9 Calibration The 1522 should be calibrated a t regul ar interv als to ensure t hat it continues to measure with proper accuracy . Calibration should only be done by qualified, authorized personnel. 9.1 Required Equipment The follo wing items are required to test and calibrat e the 1522: • 0 Ω four-wire resistor (short) • 25 Ω four-wire resis[...]

  • Página 54

    4. V erify the accuracy at 0 Ω , 4k Ω ,1 0k Ω ,4 0k Ω , 100 k Ω , and 500 k Ω . 5. Set the meter calibration date to the present date (see Section 7.9.18). 6. Set the meter due date to a user defined date (see Secti on 7.9.19). 1522 Handheld Thermometer Readout User’s Guide 54[...]

  • Página 55

    10 Maintenance • This instrument has been designed with the utmost care. Ease of operation and simplicity of maintenance have been a central theme in the product dev elopment. W ith proper care the instrument should require v ery little maintenance. A void operating the instrument in oily , wet, dirty , or dusty en vironments. • If the outside [...]

  • Página 56

    11 T r oubleshooting In case you run into dif ficulty while operat ing the 1522, this sect ion provides some suggestions that may help you solve the probl em. Belo w are sev eral situa - tions that may arise follo wed by possible causes of the problem and suggested actions you might take . 11.1 An Error Message Is Display ed The follo wing table li[...]

  • Página 57

    Problem Solution While attempti ng to measure re - sistance the display shows an i n - correct value. Poor or incorrect connecti on of the probe. A common mista ke is to connect the wires of t he probe to the wrong t erminals. Check the wir - ing carefully ( see Figure 7). Open, shorted, or damaged sensor or lead wires. Check the resi s - tance acr[...]

  • Página 58

    a) Set up the terminal program to use the correct COM port and operate at 2400 baud, 8 data bits, 1 stop bit, no parity, no flo w control. b) If you want to sav e the downloaded data to a file, conf igure your ter - minal program to capture the incoming text and save it to a te xt file. Refer to your terminal program 's documentation for detai[...]

  • Página 59

    sion. For best results , place the IR dongle and the IR windo w on the 1522 at an angle of 0° and within 0.5 meters. 11.4 CE Comments 11.4.1 EMC Directive Hart Scientific’ s equipment has been tested to meet the European Electromag- netic Compatibility Directiv e (EMC Dir ectiv e, 89/336/EEC). The Declaration of Conformity for your instrument li[...]

  • Página 60

    Electric F ast T ransit (EFT , Burst, IEC 61000-4-4). If the instrument is sub - jected to EFT conditi ons at 2kV , the instrument may require the user to c ycle the power to return to normal operation. 11.4.1.2 Emission T esting The instrument fu lf ills the limit requirements for Class A equip ment b ut does not fulfi ll the limit requirements fo[...]