A IM & THU RL BY TH ANDAR INSTRUM E NTS BS407 Wide range precision micro-ohmmeter High basic accuracy of 0.1% Wide measurement range of 1 W to 20k W Current reversal switch for detecting thermal emf effects Current diversion switch for easy zero setting Four terminal measurement using Kelvin clip leads Battery operation with built-in charger Switchable 20mV clamp for `dry circuit' testing BS407 wide range precision micro-ohmmeter A dedicated but versatile instrument Rapid 4-terminal measurement The BS407 is an instrument which is fully optimised for the task of accurate measurement of low resistances with a best resolution of 1W. It has applications beyond the testing of components such as measuring the resistance of motor or transformer windings, the properties of materials, the thickness of plates, the security of pipework joints or wiring installations and many others. It uses a Direct Current technique to measure true resistance, rather than the resistive component of impedance which is shown by AC excited RLC bridges. The test current for each range has been carefully chosen to minimise heating of the sample under test while being sufficient to minimise the effects of thermal emf and noise. This gives much greater accuracy at low resistances than can be obtained from the very low test currents used by general purpose high resolution multimeters. The low-noise low-drift bipolar amplifiers employed need much less noise filtering than alternative chopper stabilised technologies resulting in faster settling to the correct reading. The BS407 uses a four terminal measurement system via high quality Kelvin Clip leads (supplied). For speed and convenience front panel switches are provided for current diversion (allowing in-situ zero adjustment) and current reversal (for identifying thermal emf errors). An indicator lamp confirms correct flow of the measuring current thus preventing spurious results from being recorded. Battery operation with built-in charger The BS407 is a fully portable instrument which operates from NiMh rechargeable batteries. The battery charger is built into the instrument and can be operated continuously during bench use. o Accuracies apply for a one year period over a temperature range of 18 C to o 28 C after a warm-up period of 5 minutes with the instrument and test cono nections in thermal equilibrium. Tempco outside this range <45ppm/ C Range The BS407 has eight push-button selected decade measurement ranges from 1.999mW up to 19.99kW. This unusually wide range makes it suitable for a greater variety of applications than other micro-ohmmeters. A front panel operated `clamp' switch is available to limit the maximum voltage across the unknown to 20mV. This is a requirement for the measurement of switch contact resistances to international standards. High resolution and accuracy With a lowest range of 1999W the BS407 can resolve down to one micro-ohm. Rapid settling minimises delay between readings. Precision analogue circuitry ensures a high measurement accuracy of up to 0.1% of reading 0.1% of scale. PROTECTION RANGES AND ACCURACY Resolution Test Current F.S. Voltage Accuracy 250 mA 500 V 0.1% reading 0.4% scale 1 W 1999 W Wide measurement range 1 mV 0.1% reading 0.2% scale The instrument is protected against the back-emf of its own test current from any inductance and against external short-term connection to voltage sources up to 50V. Protection against greater abuse is provided by non-flammable fusible resistors. POWER SOURCE 19.99 mW 10 W 50 mA 199.9 mW 100 W 10 mA 2 mV 0.1% reading 0.1% scale Battery 1999 mW 1 mW 5 mA 10 mV 0.1% reading 0.1% scale 19.99 W 10 mW 500 A 10 mV 0.1% reading 0.1% scale Four internal Ni-MH cells (non removable). Operating time depends upon the test current flowing - >150 hours with no test current, > 8 hours with maximum test current (1999W range). Low battery indication in display. 199.9 W 100 mW 50 A 10 mV 0.1% reading 0.1% scale AC Line 1999 W 1W 50 A 100 mV 0.1% reading 0.1% scale Built-in battery charger allows instrument operation while re-charging. Nominal re-charge time 12 hours. 19.99 kW 10 W 10 A 200 mV 0.1% reading 0.2% scale FACILITIES Display: Casing: Power: 20mV Clamp Operated by front panel switch. Limits the open circuit voltage across the unknown to 20mV (+0mV, -4mV) for "dry circuit" testing of switch and relay contacts. Not available on the 2000W and 20kW ranges. Reverse Polarity Operated by front panel switch. Reverses the polarity of the test current, enabling thermal emf effects to be detected and quantified. Set Zero Rotary offset control. A front panel switch can be used to divert the test current way from the unknown, allowing zero adjustment to be undertaken with the test leads in place. MEASUREMENT SOURCE Source EMF Compliance GENERAL 18 mV 2mV with 20mV Clamp Active < 6V with 20mV Clamp Inactive > 1V (> 0.5V on 1999W range). Compliance is the maximum voltage that can be tolerated from additional resistance in series with the force connections Operating Range: Storage Range: Environmental: Electrical Safety: EMC: Size: Weight: 3.5 digit LCD with 12.5mm characters. ABS casing with metal tilt stand giving approx. 15o angle. 220 - 240V, 110 - 120V or 100V 10%, 50/60Hz, adjustable internally; 20VA max. Installation Category II. o o +5 C to + 40 C, 20% to 80% RH. o o -10 C to +50 C Indoor use at altitudes to 2000m, Pollution Degree 2. Complies with EN61010-1. Complies with EN61326. 220(W) x 88(H) x 230(D) mm, (10.3 x 3.4 x 9.2") excluding feet and tilt stand. 1.3 kg (3lb). ACCESSORIES SUPPLIED Supplied with Kelvin Test Clip Leads, Operating Manual, IEC Mains Lead OPTIONAL Carrying Case Thurlby Thandar Instruments Ltd. operates a policy of continuous development and reserves the right to alter specifications without prior notice. Designed and manufactured in Europe by: Thurlby Thandar Instruments Ltd. Glebe Road, Huntingdon. Cambs. PE29 7DR U.K. Tel: +44 (0)1480 412451 Fax: +44 (0)1480 450409 Email: info@aimtti.com Web: www.aimtti.com 82100-1130 Iss. 1A Product Summary Company name and product brands Laboratory Power Supplies Bench and system power supplies from 30 watts up to 1200 watts using linear, mixed-mode and PowerFlex regulation technologies. Thurlby Thandar Instruments Ltd. (TTi) is one of Europe's leading manufacturers of test and measurement instruments. Waveform Generators Analog and digital (DDS) function generators, true arbitrary generators, arbitrary/function generators and pulse generators. In the future, however, the full product range will be branded Aim-TTi. Products have been sold under two brand names: TTi and Aim. This changeover will be gradual and many products will continue to carry the TTi or Aim brands for some time to come. Web Addresses (URLs) Precision Measurement Instruments Benchtop DMMs, frequency counters, component measurement instruments (LCR), electronic dc loads, current probes. The preferred URL for obtaining information concerning Aim-TTi products is: www.aimtti.com (international customers) Customers in the UK should use the URL: www.aimtti.co.uk RF and EMC Test Equipment Spectrum analyzers, signal generators, frequency counters, power meters, emc measurement instruments. Customers in the USA should use the URL: www.aimtti.us Note that previous URLs such as www.tti-test.com will continue to operate for the time being. Designed and built in Europe by: Thurlby Thandar Instruments Ltd. Glebe Road, Huntingdon, Cambridgeshire PE29 7DR England (United Kingdom) Tel: +44 (0)1480 412451 Fax: +44 (0)1480 450409 Email: info@aimtti.com Web: www.aimtti.com