846 User Manual - Electro Tech Systems
Contents
1. single electrode assembly to the part to be measured Follow the measurement procedure above To calculate the volume resistivity multiply the measured resistance by the area of the electrode 64cm divided by the thickness of the material in cm refer to Section 3 1 CALIBRATION The Model 846 Clamp Electrodes incorporate a force adjustment screw that allows the user to vary the clamping force from 1 to 50 Ibs Figure 4 0 1 shows the location of the adjusting screw Turning the screw clockwise increases the force The force is preset at the factory to 20 lbs One method for establishing the desired force is to place an equivalent weight onto one handle while the other handle rests on a rigid surface Adjust the screw until the jaws just start to open Figure 4 0 1 Force adjustment 6 07 5 0 WARRANTY Electro Tech Systems Inc warrants its equipment accessories and parts of its manufacture to be and remain free from defects in material and workmanship for a period of one 1 year from date of invoice and will at the discretion of Seller either replace or repair without charge F O B Glenside similar equipment or a similar part to replace any equipment or part of its manufacture which within the above stated time is proved to have been defective at the time it was sold All equipment claimed defective must be returned properly identified to the Seller or presented to one of its agents for inspection This warranty only a2. MODEL 846 ELECTRODES FOR TESTING CONCRETE PANEL FLANGEWAY FILLER AND OTHER RESISTANCE MEASURING APPLICATIONS Operating Instructions 1 0 GENERAL DESCRIPTION The Model 846 Clamp Electrodes shown in Figure 1 0 1 is designed to test concrete panel flangeway filler blocks in accordance with Union Pacific Railroad Specification 121505 The probes feature a unique dual pad design for measuring both point to point resistance and volume resistance resistivity Figure 1 0 1 Model 846 Clamp Electrodes The electrodes are used with resistance indicators and meters having a test voltage of 500 volts AEMC Models 1035 1045 and 1060 The following specifications are for the Model 1035 electro tech systems inc 3101 Mt Carmel Avenue Glenside PA 19038 Tel 215 887 2196 Fax 215 887 0131 1 1 Model 1035 Megohmmeter Resistance Ranges lt 1 to 400 kOhms 3 of reading 1 ct Ve 7 9V 10k to 2 0 Gigohm 3 of reading 5 ct lt 40 Megohm 2 ct gt 40 Megohm Ve 50V 20k to 2 0 Gigohms Ve 100V 50k 20 Gigohm Ve 250V 100k to 20Gigohm V_ 500V Short circuit current lt 8ma Voltage Ranges 0 to 600 Volts AC or DC Audible Tone Upper lower alarm thresholds switchable ON OFF Batteries Six 6 x1 5 Volt AA alkaline Battery Life 3500 tests 5 seconds each 2 0 ELECTRODE DESCRIPTION 3 0 The Model 846 Clamp Electrodes shown in Figure 1 0 1 consists of 0 375 diameter 9mm conductive elastomer pads with volume r
3. at determines how a part dissipates a static charge Hook Up The Model 846 Clamp Electrodes can be used either in pairs using just one of the electrodes to measure the resistance across the surface of a material or alone using both electrodes to measure volume resistance The Model 846 Clamps accept standard 0 060 banana plugs Meters such as the AEMC Model 1035 utilize standard banana plugs with protective plastic cover Adapters are provided to convert these covered plugs to standard plugs Figures 3 0 1 amp 2 show each type of hook up using an AEMC Model 1035 Megohmmeter Figure 3 0 1 Surface Resistance Figure 3 0 2 Volume Resistance 3 4 Test Procedure 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Verify megohmmeter operation by performing calibration and operation checks per manufacturer recommendations Verify test set by measuring a 10 Megohm 1 resistor Read and record the ambient temperature percent relative humidity and dew point Read and record the surface temperature of the test specimen Verify that surfaces of clamps and test specimen are clean and dry Do not use a cleaner that could leave a non conductive residue Place one clamp on test specimen Read and record Date and Pressure Start Time PST the clamp was placed on specimen and pressure was applied Allow pressure on test specimen to stabilize wait at least 5 minutes before applying voltage to test spec
4. esistivity of 0 01 ohm cm and Shore A hardness of 65 durometer The pads are mounted to stainless steel electrodes installed onto an insulated clamp having a resistance gt 10 Ohms exerting approximately 20 pounds 9kg of force The smaller electrode can be inserted up to 1 5 838mm into a formed block When measuring surface resistance one pad from each clamp is used When measuring volume resistance both pads from a single clamp are used Standard 162 banana jacks are located on the sides of each handle Standard cables with banana plugs supplied with the resistance meters are satisfactory for making the resistance measurements USING THE ELECTRODES 3 1 Characteristics of Insulation Material When testing insulation material the current flowing through the material has three components Capacitance Charging Current which starts out at a high level and drops after the insulation has been charged to full voltage Absorption Current also an initially high level but then drops and is based on the absorption effect of good insulation compared to that of moist or contaminated insulation Finally Leakage Conduction Current is a small steady current that flow both through and over the insulation 3 2 With good insulation the conductance or leakage current should build up to a steady value that is constant for the applied voltage Since readings are time dependent electrification time the reading is apparent resistance The co
5. fore a resistance measurement can be made Once this occurs the actual resistance of the part may be lower than the measuring range of the instrumentation used In essence these materials are non linear and voltage dependent Hence different test voltages will give different results Even the series resistor incorporated in virtually all resistance meters are different from meter to meter may cause variations in the measurements Loaded thermoelectric material is generally not adversely affected by humidity as long as it is reasonable such as less than 75 Currently ESD materials are classified as follows Conductive Dissipative Insulative Surface lt 10 10 to lt 10 gt 10 Ohms Volume same 3 3 Materials with bulk resistance characteristics can also be classified by specifying its volume resistivity This is simply done by multiplying the measured resistance by the area of the measuring electrode or material surface whichever is smaller and divided by the thickness Pv Alt Rm Q cm All values are in cm giving a volume resistivity in Ohms cm The area of the measuring electrodes is 0 64 cm To convert to Ohms meter multiply by 100 Increasing or decreasing the thickness of the material will also change the actual resistance of the part with a specified volume resistivity This is a common technique used in ESD products to achieve a particular resistance It is the actual resistance of the part not its resistivity th
6. imen Connect clamp leads to megohmmeter Insulation resistance measurements will be in error if residual charges exist on the insulation A residual charge will show as a reverse deflection of the insulation resistance meter after connections are made but before voltage is applied Therefore prior to measuring the insulation resistance the test specimen must be completely discharged An air ionizer will effectively discharge any residual charge on an insulator Select a DC voltage of 500 volts to be applied as the standard test voltage Read and record the Test Voltage Read and record the Electrification Start Time EST the time the megohmmeter was turned on Start Test turn megohmmeter Test Voltage ON Read and record the Insulation Resistance IR at 30 seconds Read and record the Insulation Resistance IR at 1 minute Read and record the Insulation Resistance IR at 10 minutes Stop test turn megohmmeter Test Voltage OFF Read and record the Total Time TT that the sample was under pressure in the test fixture Disconnect clamp leads from megohmmeter Calculate and record the Dielectric Absorption Ratio DAR 60 30sec ratio Calculate and record the Polarization Index PI 10 1min ratio The minimum Insulation Resistance IR after 10 minutes must be greater than 10 Meg ohms Repeat for every 5th batch 1 batch is approximately 400 to 600 pounds or as needed 4 0 To measure volume resistance clamp a
7. kaging If the original packaging is not available the equipment must be packed in a sufficiently large box or boxes if applicable of double wall construction with substantial packing around all sides The RMA number description of the problem along with the contact name and telephone number must be included in formal paperwork and enclosed with the instrument Round trip freight and related charges are the owner s responsibility
8. nductivity of the rubber will also change with applied pressure Therefore insulation testing of rubber used for filler between concrete crossing panels and rails must also be tested with the rubber under pressure Characteristics of Static Dissipative and Conductive Material Thermoformed plastics that are rendered static dissipative or conductive consist of a plastic resin filler with very high resistance properties loaded with a small percentage of a conductive material such as stainless steel fibers or carbon powder or fibers These materials have bulk resistance properties verses the surface only resistance properties found in other ESD materials When a voltage is applied either across or through the material the dielectric of the filler breaks down and current flows from particle to particle As the loading of the conductive medium decreases there is greater distance between particles that requires a higher voltage to break down the increased dielectric At some point once a higher voltage is applied to establish continuity the resistance of the path created may become altered permanently Loaded thermoplastic materials are effective in reducing the upper resistance limit to approximately 108 Ohms Another characteristic associated with loaded thermoplastic materials that affects measuring it s resistance is the microscopic insulative layer that develops on the surface of the molded part The dielectric of this layer must be broken down be
9. pplies to equipment operated in accordance with Seller s operating instructions Seller s warranty with respect to those parts of the equipment which are purchased from other manufacturers shall be subject only to that manufacturer s warranty The Seller s liability hereunder is expressly limited to repairing or replacing any parts of the equipment manufactured by the manufacturer and found to have been defective The Seller shall not be liable for damage resulting or claimed to result from any cause whatsoever This warranty becomes null and void should the equipment or any part thereof be abused or modified by the customer of if used in any application other than that for which it was intended This warranty to replace or repair is the only warranty either expressed or implied or provided by law and is in lieu of all other warranties and the Seller denies any other promise guarantee or warranty with respect to the equipment or accessories and in particular as to its or their suitability for the purposes of the buyer or its or their performance either quantitatively or qualitatively or as to the products which it may produce and the buyer is expected to expressly waive rights to any warranty other than that stated herein ETS must be notified before any equipment is returned for repair ETS will issue an RMA Return Material Authorization number for return of equipment Equipment should be shipped prepaid and insured in the original pac
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