TEGAM INC. MODEL M-1011A and M
Contents
1. INC MODEL M 1011A and M 1012A AC RATI O STANDARD Instruction Manual PN M 1011A 840 01 Publication Date J une 2008 REV A INC MODEL M 1011A and M 1012A AC RATI O STANDARD Instruction Manual PN M 1011A 840 01 Publication Date June 2008 REV A NOTE This user s manual was as current as possible when this product was manufactured However products are constantly being updated and improved Because of this some differences may occur between the description in this manual and the product received Section I II III IV VI CONTENTS Page GENERAL DESCRIPTION lul PUR D OSS V ete PIRE D IM ardet err nd 1 1 ISZ General Description sedere ACE P Pe be Eo P Fx Tier 1 1 13 Optional Accessories harees ote ere EE esa dT pH SE 1 2 INSTALLATION 2p r IntroductiDD coe EV E rte eM 2 1 2 2 Maintenance TOO S odio oed eoo 2 1 2 3 asini RARA IRR re 2 1 CONTROLS SWITCHES AND TERMINALS Sl IDEFOGCUCEIORI dite ciao veces Loco dea aa bend 3 1 3 2 Controls Switches and Terminals Ie dei basen peces pur e 3 1 INSTALLATION 4 D ety oe at vie E ENTE 4 1 4 2 4 2 dn eiut rtu eR e M Seer 4 1 4 2 RACK RTT 4 1 4 2 4 4 Operating POWBLI2. 041 Resistor Composition 2 2 2K ohms 10 1 2W 964005 009 Lockwasher 3 8 Int Tooth 2 964006 011 Hex Nut 3 8 32 7 M 1012A 051 Front Panel Assy 1 100564 001 Washer 2 M 1012A 330 Front Panel 1 203002 001 Bracket 2 203053 001 Window 7 941018 001 Binding Post Red 4 941018 002 Binding Post White 2 941018 003 Binding Post Black 2 964006 006 Hex Nut 8 32 4 964025 006 Washer Flat 375 OD 4 964066 005 Washer Spring Lock 8 4 8 7 Section IX SCHEMATI C DI AGRAMS 9 1 INTRODUCTI ON Section contains a Schematic Diagram for the Models M 1011A and 1012 AC Ratio Standard instruments 9 1 9 2 VeTOI W YO VIIOI MW STICON WYYOVIC OILVW3HOS 1 6 3Bh5IJ so SS S ES 25 15 n 9 01 5 01 01 2 01 1 0 35953 yua 2 p NUE INDYI I wa ma z ava 5 NOWWOS NOWHOD TA 5 c Nag 2 CINDY i e ms 9 CLNDY4 gt DIA P x x x TIU NIE LHM CIY NTE LHM 1HA NNE NS J a V 3sv3 9 3
3. MAINTENANCE TOOLS 1 Phillips Head Screwdriver 2 Contact Cleaner 2 3 SPECIFICATIONS Refer to Tables 2 1 and 2 2 Table 2 1 Model M 1011A Specifications CHARACTERISTIC SPECIFICATIONS Maximum rms Input Voltage 0 35 f f in Hz or 350 volts whichever is less Ratio Range Maximum 1 111111 Minimum 0 0111111 Accuracy of Indicated Ratio 50 to 1 000 Hz 0 0001 0 000025 0 000025 Above 1 kHz 0 000190 E UO x F2 where F is in kHz Terminal Linearity 0 0001 1ppm or better above 1 kHz multiply by F in kHz Table 2 1 Specifications Cont CHARACTERISTIC SPECIFICATIONS Maximum Effective Series R 3 5 ohms Output Impedance L 75 pH Input Impedance at 20 V and 400 Hz 200 K minimum Dimensions Bench Operation 43 2 cm 17 wide 14 9 cm 5 7 8 high 42 8 cm 16 7 8 deep including feet and handles Rack Mounted 48 3 cm 19 wide 13 3 cm 5 1 4 high 38 4 cm 15 1 8 deep depth from back of rack mounting ears to end of back panel terminals 2 2 Table 2 2 Model 1012 Specifications CHARACTERISTIC SPECIFICATIONS Frequency Range 30 to 1 000 Hz Maximum rms Input Voltage 2 5 f f in Hz or 350 volts whicheverr is less Ratio Range Maximum 1 111111 Minimum 0 0111111 Resolution 0 00001 Accuracy of Indicated Ratio 0 00005 30 to 400 Hz 0 0001 Terminal Linearity 0 0001 1 ppm or better Maximum Effective Series R 5 ohm
4. Qty 104561 001 Bezel 2 203052 001 Chassis 1 203076 001 Bracket Cover 2 203077 001 Cover Slide 2 203078 001 Cover Top 1 203192 001 2 404444 001 Dial 7 404499 001 Knob 7 966050 001 Frame Side 2 964003 028 Screw Mach PH 6 63X3 8 4 964003 045 Screw Mach PH 8 32X1 2 8 964006 005 Hex Nut 6 32 3 964025 005 Washer 312 OD 7 964025 006 Washer 375 8 964064 028 Screw Mach 6 32x3 8 26 964066 004 Washer Lock 6 7 964066 005 Washer Lock 8 8 6093 001 Rear Panel Sub Assy 1 100564 001 Washer 2 203040 001 Rear Panel 1 F1 F2 924000 022 Fuse 1 5 amphere 2 XF1 XF2 924001 001 Fuse Holder 2 941018 001 Binding Post Red 4 941018 002 Binding Post White 2 941018 003 Binding Post Black 2 S8 951036 027 Toggle Switch 1 6113 002 Bottom Cover Assy 1 203079 001 Bottom Cover 1 964003 028 Screw Mach PH 6 32x3 8 2 964003 029 Screw Mach PH 6 32x7 16 4 964024 005 Screw Mach FH 4 40x7 16 6 8 6 TABLE 8 4 Parts List Model 1012 continued Ref TEGAM Total Desig Part No Description Qty 964025 005 Washer Flat 312 ID 6 964066 004 Washer Spring Lock 6 6 964118 104 Tilt Bail 1 006144 001 Switch Sub Assy 1 1 1859 001 Transformer Toroid 1 2 1860 001 Transformer Toroid 1 203044 001 Switch Bracket 1 S1thru S7 402180 001 Rotary Switch 7 R5 R7 945001 021 Resistor Composition 4 R9 R11 47 ohms 1096 1 2W R1 R3 945001
5. USED is placed in the column In these instances column 2 is left blank Refer to Table 8 2 on abbreviations that are used in the Parts List Total Quantity Column 4 The total quantity used of each Part Number listed 8 2 TABLE 8 1 Reference Symbols A Assembly R Resistor C Capacitor S Switch F Fuse T Transformer K Relay W Cable Inductor XF Fuse Holder TABLE 8 2 Abbreviations A Ampere mH ___Millihenry AC Alternating Current No Number Desig Designator Ref Reference Hz Hertz V Volts k Thousand 103 W Watts Mfr Manufacturer if sign not shown 8 3 TABLE 8 3 Parts List for Model M 1011A Ref TEGAM Total Desig Part No Description Qty 104561 001 Bezel 2 203052 001 Chassis 1 203076 001 Bracket Cover 2 203077 001 Cover Slide 2 203078 001 Cover Top 1 203192 001 2 404444 001 Dial 7 404499 001 Knob 7 966050 001 Frame Side 2 964003 028 Screw Mach PH 6 63X3 8 4 964003 045 Screw Mach PH 8 32X1 2 8 964006 005 Hex Nut 6 32 3 964025 005 Washer 312 OD 7 964025 006 Washer 375 8 964064 028 Screw Mach 6 32x3 8 26 964066 004 Washer Lock 6 7 964066 005 Washer Lock 8 8 6093 001 Rear Panel Sub Assy 1 100564 001 Washer 2 203040 001 Rear Panel 1 F1 F2 924000 022 Fuse 1 5 amphere 2 XF1 XF2 924001 001 Fuse Holder 2 941018 001 B
6. applied to Model 1011 with a ratio setting of 0 820000 Determine the total percent error at a test freqency of 5 kHz an 10 000 ohms and an Xjgaq7 j31 41 ohms 1 0 mH where the unloaded error is 0 003262 see accuracy of indicated ratio Table 2 1 z 10 000 x 31 41 2 10 000 049 From Table 2 1 Maximum Effective Series Output Impedance is 3 5 ohms and 75 10 000 ohms 3 5 ohms 10 003 5 ohms A j31 41 ohms j2x 5 x 103 x 0 075 x 1073 j33 766 ohms 10 003 5 2 j33 766 10 003 557 ohms E 10 000 049 output 10 003 557 x 82 00 81 971V 95 Load Error 82 00 81 971 V x 100 0 03536 82 00 Total Error 0 03536 0 003262 0 03862 NOTE The example gives a loaded error 11 8 times greater than the unloaded error However this is not an indeterminate 5 7 error By correcting the Model 1011 dial setting indication by the computed difference of E output the 0 003262 unloaded accuracy is substantially returned 5 5 EFFECTS OF EXCESSIVE INPUT VOLTAGE The maximum rms input voltage rating must be observed in order to prevent core saturation Input voltage in excess of rating will cause core saturation resulting in the permeability of the core material to drop sharply to almost zero The input impedence will drop correspondingly resulting in excess input current If driven by a low impedance source the input fuse will blow thereby protecti
7. ON The following instructions will aid in ordering parts a Address all inquires or orders to CUSTOMER SERVICE DEPARTMENT TEGAM Inc 10 Tegam Way Geneva Ohio 44041 Include the following information 1 Model and Serial Number of instrument 2 Assembly Reference Symbol Number 1 1 3 Reference Designation Number i e C1 4 TEGAM Part Number 5 Description as shown on Parts List Packing No special handling or packing procedures are required It is suggested you pack the instrument in a crash resistant box 8 1 8 3 PARTS LIST USE The Table of Contents at the front of the manual lists the Parts List Tables related assemblies and location The following paragraphs describe the use and meaning of the four columns included in the Parts List starting with Table 8 3 a Reference Designation Column 1 The Reference Designation column contains an alpha numeric listing of parts as they appear on the equipment chassis illustration or schematic The reference designation identifies the parts as to their component function in the instrument Refer to Table 8 1 TEGAM Part Number Column 2 The TEGAM Part Number column contains the part number as designated by TEGAM Description Column 3 The Description column contains the identification of component parts including all pertinent specifications When the description column is used for a reference symbol for which no part exists NOT
8. S udi osito elo ngu 4 1 4 2 OPERATION ble Introduction sca ssec ox e ta eu EE Dd Ens Mas DAS EE 5 1 5 2 Connection to the AC Ratio Standard cocer osx er oia t ni 5 1 So Operation 5 1 AN General 5 1 5 3 2 ato roce le Eee i br RC dr 5 3 5 4 Accuracy Under Lodd CordibloHis e eR EET ER End 5 5 ARE m 5 5 5 4 2 1boatling Brror Computation Saiko iii e EAE em es oc tbe oa 5 6 5 5 Effect of Excessive Input een a v TEE TEE ERE 5 8 THEORY OF OPERATION bi TE 6 1 6 2 Theoretical Analysis of ACCURATA i Pea 6 2 6 3 Ratio Stanidard ACCUFaCy 6 4 CONTENTS Cont Section Page VII MAINTENANCE Td a ansi 7 1 Tg SSWitch rontacis lella re 7 1 Z Degaussingss IA RIE 7 1 7 4 Calibration Check co eee oe eoe Gr n eene ur a E EEO 7 3 7 4 1 Impedance Checks scien eto teste esas ees e e PR CORE DERE INS 7 4 7 42 Ratio Accuracy Testi cec exec eta eb a e Pare ce a e X UR UN 7 5 VIII REPLACEABLE PARTS Introductionis ee e aad ees eo UR ERE RR 8 1 8 2 Ordering Informations roce uo dro teo eaa teet ve ox ta
9. ce 0 1 ratio tap terminal Chassis case grounding terminal 24 FUSE S8 Shorting toggle switch for removing IN OUT INPUT FUSE F1 from the input circuit OUT position CASE GND Chassis case grounding terminal 26 COMMON Common output circuit terminal zero output voltage reference 3 3 4 1 4 2 4 3 Section IV I NSTALLATI ON UNPACKI NG No special handling or unpacking procedures are required After unpacking inspect units for any evidence of damage BENCH OPERATI ON The AC ratio standard is shipped ready for use as a bench operated instrument A folding support that is attached to the feet under the front of the instrument may be pulled down to elevate the front of the instrument for ease of operation RACK MOUNTING Rack mounting option 11 TEGAM part number OPT 11 is available at extra cost Option 11 consists of a set of adapter brackets and attaching screws that permits mounting the AC ratio standard into a standard 19 inch rack To prepare the instrument for rack mounting proceed as follows a Remove the six screws that attach the four feet and folding support to the bottom of the instrument Retain the screws feet and support for future use b Attach one rack mounting bracket Part No 964729 003 1 to each side of the instrument using two 10 32 X 3 8 flat head screws Part No 964064 263 and three 6 32 x 3 8 flat head screws Part No 964064 028 in each bracket Note that you will ne
10. e from the factory 5 1 1 1 1 111111 OUTPUT COMMON 0 0 0111111 COMMON STANDARD CONNECTION 11 1 1 1 111111 OUTPUT RATIO INPUT OUTPUT NOT USED COMMON 3 0 0111111 Ganon 1 1 RATIO VOLTAGE CONNECTION 1 1 1 111111 INPUT OUTPUT NOT USED COMMON COMMON 0 0111111 1 OUTPUT RATIO 1 RATIO VOLTAGE CONNECTION Figure 5 1 Ratio Standard Configurations 5 2 INPUT O RATIO STANDARD VOLTAGE SOURCE PHASE ANGLE VOLTMETER UNIT INPUT UNDER TEST Figure 5 2 Typical Application 5 3 2 Operation To operate the AC Ratio Standard proceed as follows a Throw the back panel mounted FUSE toggle switch to IN position WARNING A shock hazard exists on the instrument s input terminals when voltage levels exceed 30V rms or 42 2V peak b Connect input or reference voltage source to the INPUT and adjacent COMMON terminals Make certain the input voltage is less than 0 35 time the frequency in Hz for the M 1011A or 2 5 time the frequency in Hz for the M 1012A of the input signal or 350 volts whichever is less Refer to Paragraph 5 5 for information of excessive voltage 5 3 CAUTION Make certain the input voltage does not contain a dc component DC currents of more than a few microamperes will cause saturation of the input winding If dc voltage is accidentally applied to the unit degauss the unit as outlined in the maintenance section Parag
11. e phase error as well as magnitude error The fact that this error voltage is in quadrature makes the magnitude error extremely small and for all practical purposes negligible Typical figures might be 00000196 for small ratios and even less for larger ratios Phase angles from this cause would be approximately 01 milliradians at low frequencies and small ratios decreasing for larger ratios At higher frequencies distributed capacitance becomes important It causes voltage drops in the leakage inductance and winding resistance which are not uniformly distributed due to the transformer action Like the effects of winding resistance the errors caused by the capacitance are mainly in quadrature and so cause phase shift at low ratios Typical values for this phase shift are Less than 05 milliradians for frequencies below 1 kHz and Ratios above 1 for low voltage high frequency units Less than 05 milliradians for frequencies below 200 Hz and ratios above 1 for high voltage low frequency units Phase angle due to this cause is almost directly proportional to frequency for any particular ratio down to frequencies where the non distributed resistance takes over Another source of error is voltage drop due to exciting current in the leads to the transformer This effect may be minimized by using heavy connecting leads or treating the transformer as a four terminal impedance The internal wiring of the transformers contributes to this error T
12. ed to remove the two 6 32 screws securing the side frame to the front panel to install the new 6 32x3 8 flat head screw 4 4 OPERATING POWER No operating power is required however excitation voltage is required during operation refer to Tables 2 1 and 2 2 4 1 4 2 5 1 5 2 5 3 5 3 1 Section INTRODUCTI ON Instructions for operating the AC ratio standard models are presented in this section Refer to Section 111 for descriptions of the operating controls switches and terminals Refer to Section IV for installation information CONNECTI NG TO THE AC RATIO STANDARD Three output circuit configurations are available to the user All configurations have the same direct input connection and provide in phase output voltage Choice of output circuit is controlled by which terminals are used Refer to Figure 5 1 for abbreviated schematics of the three Ratio Standard configurations OPERATI ON General A typical application of the Ratio Standard is shown in Figure 5 2 The output of the Ratio Standard is compared to the output of the unit under test using a phase sensitive null indicator such as a phase angle voltmeter TEGAM Model PAV 4 When the in phase components of the two outputs are exactly equal the phase angle voltmeter indicates a null The input to output voltage ratio of the unit under test may then be read from the settings of the Ratio Standard Additional applications are availabl
13. ed by age or environmental conditions The Model M 1012A is identical to the Model M 1011A except it is designed specifically for the 30 Hz to 1000 Hz frequency range The AC ratio standard consists of seven tapped windings Portions of the input voltage are selected from the tapped windings by rotary switches These portions are added together to form the output voltage All ratio standard controls and connection points are mounted on the front panel An additional set of connection points are mounted on the back panel Both input and output circuits are fused with the fuse holders mounted on the back panel Switching transients are virtually eliminated by resistors which maintain continuity between steps while settings are being changed 1 1 The AC ratio standard provides maximum ratios up to 1 111111 minimum ratios as low as 0 0111111 with seven place resolution Additional terminals provide ratio taps of 1 1 and 0 1 The ratio accuracy of the standard is based upon the use of a toroidal autotransformer which is not affected by age or environmental conditions Accuracy is traceable to the National Institute of Standards and Technology 1 3 OPTIONAL ACCESSORIES Option 11 TEGAM part number OPT 11 is a rack mount adapter for A models refer to Paragraph 4 3 1 2 Section II SPECIFICATIONS 2 1 INTRODUCTION This section contains specification information for the AC Ratio Standard Models M 1011A M 1012A 2 2
14. er With reference to the equivalent circuit Figure 5 3 we see an ideal transformer with a series impedance Rs and L5 inserted in the output arm The series impedance is due to leakage inductance wiring resistance switch resistance potentiometer resistance and other stray circuit elements Rs and Lsvary with the ratio setting but only the maximum value is specified refer to Table 2 1 Maximum Effective Series Output Impedance From Ls the effect of loading upon the transformer accuracy can be calculated see Paragraph 5 4 2 The resulting loading error must be added to the no load ratio accuracy of the ideal transformer to obtain the accuracy at the output terminals 5 5 E RatioTran E Output Y Figure 5 3 Equivalent Circuit Direct Connection 5 4 2 Loading Error Computations Referring to Figure 5 3 E u equals E when the output is tput unloaded When a load is added the current flow through Rot develops Ratiotran a voltage drop and an Pu error The following formula may be used tput in determining the output voltage error 2 R 2 X Load Impedance L load load R R R Total Resistance load 5 X X 2nfL Total Reactance T load 5 _2 _ 2 Total Impedance T T T 2 L output 2 xE T RatioTran E E Load Error Ratio Tran out x 100 E Ratio Tran 95 Total Error Load Error no load ratio accuracy 5 6 Assume 100 V
15. h contacts no maintenance on a regularly scheduled basis is required Moving parts are lubricated at the factory and should require no further lubrication SWITCH CONTACTS During Calibration Intervals clean switch contacts with a good grade of solvent such as alcohol or acetone Relubricate contacts with a small amount of light lubricant DEGAUSSI NG If dc voltage is accidently applied to the input terminals degauss the unit as follows a Connect a 1K resistor in series with the INPUT terminal b By means of a variac or other suitable voltage control apply a 60 Hz signal between the open end of the 1K resistor and the COM terminal Starting with the voltage control at zero increase voltage to 40 V rms d Slowly decrease the voltage to zero The period of time to reduce the voltage from 40 V rms to zero should be between 10 to 15 seconds 7 1 5105 5106 5104 5103 The Model M 1012A is the same except for the size of T1 and T2 and the model number Figure 7 1 Location Of Components Model M 1011A Top View 7 2 7 4 CALIBRATION CHECK Provided that the AC Ratio Standard is kept in a normal laboratory environment the unit should only require a calibration check every three years Under more severe conditions the calibration period must be shortened This section includes two tests an input impedance test and a simplified ratio accuracy test Refer to Table 7 1 for a list of test e
16. hese effects are worst at higher frequencies above the self resonant frequencies of the transformers 6 3 6 3 AC RATIO STANDARD ACCURACY The AC Ratio Standard accuracy is presented in two ways The first is called Terminal Linerarity the same term used for describing potentiometer accuracy The usual definition of terminal linearity is error in the output divided by the total input Terminal Linearity SAEG in where AE is the actual error voltage in the output and E is the total input voltage in The second way that accuracy is presented is in terms of output voltage It is called Ratio Accuracy or Accuracy of Indicated Ratio Ratio Linearity A Eg ae I where AE is the actual error voltage in the output and E is the total output voltage The second accuracy approach is specified by a formula which gives the maximum error which could be expected in the indicated ratio This gives the error as a percentage of the output if the input is perfectly known This accuracy is applicable to a bridge circuit since the source voltage is common to both branches of the bridge circuit and variations of source voltage cause no error see Paragraph 7 4 2 which describes use of a bridge circuit when performing an accuracy test 6 4 7 1 7 2 7 3 Section VII MAI NTENANCE GENERAL Since AC Ratio Standards are passive devices a minimum maintenance is required With the exception of cleaning switc
17. inding Post Red 4 941018 002 Binding Post White 2 941018 003 Binding Post Black 2 S8 951036 027 Toggle Switch T 6113 002 Bottom Cover Assy 1 203079 001 Bottom Cover 1 964003 028 Screw Mach PH 6 32x3 8 2 964003 029 Screw Mach PH 6 32x7 16 4 964024 005 Screw Mach FH 4 40x7 16 6 8 4 TABLE 8 3 Parts List Model M 1011A continued Ref TEGAM Total Desig Part No Description Qty 964025 005 Washer Flat 312 ID 6 964066 004 Washer Spring Lock 6 6 964118 104 Tilt Bail 1 006148 001 Switch Sub Assy 1 1 1985 002 Transformer Toroid 1 2 1986 002 Transformer Toroid 1 203044 001 Switch Bracket 1 S1thru S7 402180 001 Rotary Switch 7 R5 R7 945001 021 Resistor Composition 4 R9 R11 47 ohms 1096 1 2W R1 R3 945001 041 Resistor Composition 2 2 2K ohms 10 1 2W 964005 009 Lockwasher 3 8 Int Tooth 7 964006 011 Hex Nut 3 8 32 7 6115 001 Front Panel Assy 1 100564 001 Washer 2 104556 001 Front Panel 1 203002 001 Bracket 2 203053 001 Window 7 941018 001 Binding Post Red 4 941018 002 Binding Post White 2 941018 003 Binding Post Black 2 964006 006 Hex Nut 8 32 4 964025 006 Washer Flat 3750D 4 964066 005 Washer Spring Lock 8 4 8 5 TABLE 8 4 Parts List for Model M 1012A Ref TEGAM Total Desig Part No Description
18. n so far as flux is concerned is the uniformly wound toroid By suitably interleaving the windings and carefully maintaining uniformity the total leakage inductances can be kept to under 1096 of the air core inductance Since the air core inductance is approximately 1 u times the inductance with iron core where u is the permeability of the core material the total leakage inductance to coupled inductance ratio is 1 10 The core material used in the transformers is supermalloy which has a guaranteed initial permeability of 100 000 The leakage to coupled inductance ratio is therefore approximately 0001 Since this figure represents the ratio of voltage dropped in the leakage inductance to total voltage the error in the transformer due to non distributed leakage inductance will not exceed this if the leakage inductance per turn does not vary by more than 100 This condition can be met with suitable techniques of interleaving the windings 6 2 Non distributed winding resistance has much the same effect as distributed leakage inductance If the effects of winding capacities are neglected the winding resistance is most important at low frequencies since the exciting impedance of the transformer is directly proportional to frequency Since the exciting impedance is fairly reactive the voltage dropped in the winding resistance will be almost in quadrature with the input and consequently any non distributed resistance will cause som
19. n wc te a RN d 8 1 So Passerelle ee 8 2 IX SCHEMATIC DIAGRAMS 9 1 EE D GR HE DG dea 9 1 9 2 ILLUSTRATIONS Figure Page 1 1 Model 1011A or 1012A AC Ratio Standard 1 0 3 1 Operating Controls Switches and Terminals Model 1011A or 1012A 3 0 5 1 Ratio Standard Configurations 5 2 5 2 Typical Application 5 3 5 3 Equivalent Circuit Direct Connection 5 6 7 1 Location of Components Model 1011A Top View 7 2 7 2 Impedance Test Setup 7 4 7 3 Ratio Accuracy Test Setup 7 6 9 1 Schematic Diagram Models 1011A or 1012A 9 3 Figure 1 1 Model 1011 or 1012 AC Ratio Standard 1 0 Section I GENERAL DESCRIPTION 1 1 PURPOSE The AC ratio standards are inductive voltage dividers providing an output voltage which is in a precise ratio to an input voltage The standard can be used to measure the output voltage of a unit under test or to duplicate the voltage ratio output required of a unit under test 1 2 DESCRIPTION The AC ratio standard is a completely contained test unit which only requires connection to an input voltage for operation The Model M 1011A is a precision voltage divider that is designed specifically for the 50 Hz to 10 kHz frequency range providing high input impedance and optimum performance thoughout this range The ratio accuracy which is traceable to the National Institute of Standards and Technology is a based on the use of a toroidal transformer and is not affect
20. nal and the COMMON terminal is precisely 1 1 times the input voltage The input winding between the COMMON terminal and the 1 terminal supplies a voltage with an amplitude precisely 0 1 times the input voltage and 180 degrees out of phase The voltage between the COMMON terminal and the 1 terminal is therefore 0 1 times the input voltage 6 1 6 2 The seven transformer windings included in two transformers The first transformer T1 contains three windings 10 107 and 107 on a common toroid core The second transformer T2 contains three windings 10 10 and 10 on one common core and the final 10 winding on a separate core Switching transients are virtually eliminated by resistors R1 R5 R7 R9 and R11 Model M 10114 and R1 through R20 Model M 10124 which maintain continuity between voltage steps while settings are being changed The switch contacts are multileaf type that have very low contact resistance Additionally each switch has four decks that are paired and wired in parallel to further reduce contact resistance THEORETI CAL ANALYSI S OF ACCURACY Theoretical analysis of a perfect autotransformer used for stepdown purposes shows that if leakage inductances and winding resistance are uniformly distributed and the turns can be accurately tapped the accuracy as a voltage divider for no load is perfect Consider first the effects of leakage inductance The most symmetrical configuration i
21. ng the transformer windings No adverse effects result from saturation once the input voltage is reduced to within rating 5 8 6 1 Section VI THEORY OF OPERATI ON GENERAL The AC Ratio Standard consists of seven tapped transformer windings and seven rotary switches Refer to the Schematic Diagram Figure 9 1 A portion of the input voltage is selected from each tapped winding and these portions are added together to form the output voltage The full input voltage is applied across the INPUT and COMMON terminals and thus across the decade portion of the input 101 winding The 10 winding and each of the remaining windings 10 through 10 are precisely tapped to provide 12 equal subwindings that will provide 12 precise voltage outputs S1 has eleven positions The lower wiper arm of S1 can select any of eleven voltages from 0 to 1 0 volts in precise 0 1 input voltage ratio steps The two wiper arms of switch S1 separated by one position applies precise 0 1 voltage portions of the 10 winding across the decade portion of the 10 winding The lower wiper arm of S2 which has 12 positions selects a 0 01 to 0 1 portion of the input voltage selected by switch S1 The process continues through the seven windings until the final and smallest portion is selected by switch S7 The input winding between the INPUT terminal and the 1 1 terminal provides a precise 0 1 step up on the input voltage The total voltage between the 1 1 termi
22. quipment required Table 7 1 Test Equipment Required NOMENCLATURE PART NUMBER APPLICATION RANGE ACCURACY OR MODEL AC Ratio Model M 1011A Provides 1 111111 to Per National Standard or Model M comparison 0 111111 ratios Institute of 1012A standard for Standards ratio test Calibration Test Bridge Model ST248 Provides signal 120 Vac 400 cps Transformer TEGAM isolation maximum Null Indicator Model PAV 4 or Provides means equivalent of comparing output voltage Decade Provides 1 megohm range 0 5 Resistance Box voltage divider network DVM Measuring 2 voltages Switch Check voltage SPDT divider network Audio Oscillator AC Voltage 20 Hz to 20KHz 0 Source to 45 VRMS 7 3 7 4 1 Impedance Check To check input impedance proceed as follows a Connect unit into test setup as shown in Figure 7 2 b Set input frequency to 400 Hz M 1011A and 60 Hz M 1012A c Adjust voltage source until DVM V1 indicates twice the desired voltage through the unit under test d Adjust decade resistance box until DVM V2 shows equal indications with switch SW 1 in either position A or B e Read input impedance from the decade resistance box The input impedance shall be 200 kilohm or more ISOLATION TRANSFORMER UNIT UNDER TEST AC POWER SOURCE Figure 7 2 Impedance Test Setup 7 4 7 4 2 Ratio Accuracy Test This procedure uses a Model M 1011A or M 1012A AC Ratio Standard a
23. raph 7 3 Make connections to the OUTPUT and COMMON terminals Refer to Figure 5 1 Standard Configuration CAUTION Do not apply voltage across the output terminals Turn the input voltage source ON Set the standard controls to the desired ratio or to the setting required to obtain a null When a null has been obtained the FUSE toggle switch may be thrown to the OUT position to provide a more accurate null measurement When a final null is obtained the input to output voltage ratio of the unit under test may then be read from the switch settings of the standard CAUTION After the ratio reading has been recorded the FUSE toggle switch should be returned to the IN position for input circuit protection 5 4 Assume the following AC Ratio Standard switch positions at null 1071 1072 1073 1074 10 107 107 6 3 1 2 7 8 5 The input to output voltage ratio would be 0 6312785 g To obtain a 1 1 ratio voltage connect the output to the 1 1 and COMMON terminals Refer to Figure 5 1 1 1 Ratio Voltage Connection h To obtain a 1 ratio voltage connectd the output to the 1 and COMMON terminals Refer to Figure 5 1 1 Ratio Voltage Connection 5 4 ACCURACY UNDER LOAD CONDITIONS 5 4 1General While the Ratio Transformer is designed for maxium accuracy in the unloaded condition reasonable loads may be applied The resulting accuracy is a function of the load and the output impedance of the transform
24. s L 350 pH Output Impedance Input Impedance at 20 V and 60 Hz 200 K minimum Dimensions Bench Operation 43 2 cm 17 wide 14 9 cm 5 7 8 high 42 8 cm 16 7 8 deep including feet and handles Rack Mounted 48 3 cm 19 wide 13 3 cm 5 1 4 high 38 4 cm 15 1 8 deep depth from back of rack mounting ears to end of back panel terminals 2 3 WARNING vot raoe musr ifr exceto MODEL MIONA kae n 36 OR 350 WOCHEVER IS LESS DO NOT Y DIRECT CURRENT DO NOT APPLY VOLTAGE TO O Figure 3 1 Operating Controls Switches and Terminals Model M 1011A or M 1012A 3 0 Section 111 CONTROLS SWITCHES AND TERMI NALS 3 1 INTRODUCTION This section contains functional descriptions of all Model M 1011A and Model M 1012A controls switches and terminals The location and purpose of the controls switches and terminals are the same for the two AC ratio standard instruments 3 2 CONTROLS SWITCHES AND TERMINALS All external controls switches and terminals of the Model M 1011A and M 1012A are located on the front and back panels Their location is identified by numbers in Figure 3 1 and their function described in Table 3 1 Table 3 1 Controls Switches and Terminals KEY PANEL DIAL REFERENCE FUNCTION MARKING DESIGNATOR 1 51 Decade switch that provides 1 X 10 1 voltage ratio steps from O to 10 X 10 x 11 positions 2 1TOX S2 Decade switch
25. s a reference To test the ratio accuracy proceed as follows a b Use test setup shown in Figure 7 3 Set input signal frequency to 400 Hz Apply an input voltage of 10 V AC as indicated on Voltmeter V1 Set the Model M 1011A or M 1012A AC Ratio Standard reference controls for an output reading of 0 0000000 Adjust unit under test controls until the Null Indicator indicates a null Compare the ratio indicated by the unit under test against the ratio indicated by the reference standard The two ratios shall agree within the Accuracy of Indicated Ratio listed in Table 2 1 Repeat steps e through f for each switch position of the reference Standard 0 1111111 0 2222222 etc 7 5 BRIDGE A BRIDGE RATIO STANDARD TRANSFORMER UNIT UNDER TEST TRANSFORMER SS 1 4 prom 1 4 NULL INDICATOR Figure 7 3 Ratio Accuracy Test Setup Not required if a PAV 4B or PAV 4C null indicator is used Bridge transformers are part of the PAV 4B and PAV 4C instrunments 7 6 8 1 8 2 Section VIII REPLACEABLE PARTS I NTRODUCTI ON This section includes all pertinent data necessary to locate identify and procure additional parts for the equipment Parts are listed alpha numerically by reference symbol and include all replaceable electronic items Satisfactory replacement may be made with either the listed component or an exact replacement of the parts s removed from the equipment ORDERI NG INFORMATI
26. that provides 1 x 10 voltage ratio steps from 1 to 10 x 10 x 12 positions 3 1TOX 53 Decade switch that provides 1 x 10 3 voltage ratio steps from 1 to 10 x 10 x 12 positions 3 1 Table 3 1 Controls Switches and Terminals Cont PANEL DIAL REFERENCE MARKING DESIGNATOR FUNCTION u u 7 1TOX S7 Decade switch that provides 1 x 10 7 voltage ratio steps from 1 to 10 x 10 7 x 12 positions 1 EE Decade switch that provides 1 X 10 voltage ratio steps from 1 to 10 x 10 x 12 positions Decade switch that provides 1 x 1077 voltage ratio steps from 1 to 10 x 10 x 12 positions Decade switch that provides 1 x 1079 voltage ratio steps from 1 to 10 x 107 x 12 positions CASE GND OUTPUT CASE GND Chassis case grounding terminal Common output circuit terminal zero output voltage reference Voltage output terminal Chassis case grounding terminal 0 1 ratio tap terminal output Common input circuit terminal zero input voltage reference Voltage input terminal 1 1 ratio tap terminal output INPUT 1 3 2 Table 3 1 Controls Switches and Terminals Cont PANEL DIAL REFERENCE MARKING DESIGNATOR FUNCTION OUTPUT Voltage output terminal UC ce 1 1 ratio tap terminal Common input circuit terminal zero input voltage referen
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