BS K-CLIP - AIM-TTI INSTRUMENTS

BS407 wide range precision micro-ohmmeter

A dedicated but versatile instrument

The BS407 is an instrument which is fully optimised for the task of

accurate measurement of low resistances with a best resolution of

1µW.

It has applications beyond the testing of components such as mea-

suring the resistance of motor or transformer windings, the proper-

ties 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 amplifi-

ers employed need much less noise filtering than alternative chop-

per stabilised technologies resulting in faster settling to the correct

reading.

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 instru-

ment and can be operated continuously during bench use.

Rapid 4-terminal measurement

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 re-

versal (for identifying thermal emf errors).

An indicator lamp confirms correct flow of the measuring current

thus preventing spurious results from being recorded.

Wide measurement range

The BS407 has eight push-button selected decade measurement

ranges from 1.999mWup 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 maxi-

mum 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 1999µWthe BS407 can resolve down to one

micro-ohm. Rapid settling minimises delay between readings.

Precision analogue circuitry ensures a high measurement accu-

racy of up to 0.1% of reading ± 0.1% of scale.

RANGES AND ACCURACY

Accuracies apply for a one year period over a temperature range of 18oC to

28oC after a warm-up period of 5 minutes with the instrument and test con-

nections in thermal equilibrium. Tempco outside this range <±45ppm/oC

Range Resolution Test Current F.S. Voltage Accuracy

1999 µW1µW250 mA 500 µV ± 0.1% reading ± 0.4% scale

19.99 mW10 µW50 mA 1 mV ± 0.1% reading ± 0.2% scale

199.9 mW100 µW10 mA 2 mV ± 0.1% reading ± 0.1% scale

1999 mW1mW5 mA 10 mV ± 0.1% reading ± 0.1% scale

19.99 W10 mW500 µA 10 mV ± 0.1% reading ± 0.1% scale

199.9 W100 mW50 µA 10 mV ± 0.1% reading ± 0.1% scale

1999 W1W50 µA 100 mV ± 0.1% reading ± 0.1% scale

19.99 kW10 W10 µA 200 mV ± 0.1% reading ± 0.2% scale

FACILITIES

20mV Clamp

Operated by front panel switch. Limits the open circuit voltage across the un-

known to 20mV (+0mV, -4mV) for “dry circuit” testing of switch and relay con-

tacts. Not available on the 2000Wand 20kWranges.

Reverse Polarity

Operated by front panel switch. Reverses the polarity of the test current, en-

abling thermal emf effects to be detected and quantified.

Set Zero

Rotary offset control. A front panel switch can be used to divert the test cur-

rent way from the unknown, allowing zero adjustment to be undertaken with

the test leads in place.

MEASUREMENT SOURCE

Source EMF 18 mV ± 2mV with 20mV Clamp Active

< 6V with 20mV Clamp Inactive

Compliance > 1V (> 0.5V on 1999µWrange).

Compliance is the

maximum voltage that can be tolerated from additional

resistance in series with the force connections Thurlby Thandar Instruments Ltd. operates a policy of continuous development and reserves

the right to alter specifications without prior notice.

PROTECTION

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 resis-

tors.

POWER SOURCE

Battery

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 (1999µWrange). Low battery indication in display.

AC Line

Built-in battery charger allows instrument operation while re-charging.

Nominal re-charge time 12 hours.

GENERAL

Display: 3.5 digit LCD with 12.5mm characters.

Casing: ABS casing with metal tilt stand giving approx. 15oangle.

Power: 220 - 240V, 110 - 120V or 100V ±10%, 50/60Hz, adjust-

able internally; 20VA max. Installation Category II.

Operating Range: +5oC to + 40oC, 20% to 80% RH.

Storage Range: -10oC to +50oC

Environmental: Indoor use at altitudes to 2000m, Pollution Degree 2.

Electrical Safety: Complies with EN61010-1.

EMC: Complies with EN61326.

Size: 220(W) x 88(H) x 230(D) mm, (10.3 x 3.4 x 9.2")

excluding feet and tilt stand.

Weight: 1.3 kg (3lb).

ACCESSORIES

SUPPLIED

Supplied with Kelvin Test Clip Leads, Operating Manual, IEC Mains Lead

OPTIONAL

Carrying Case

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

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

Designed and built in Europe by:

Company name and product brands

Thurlby Thandar Instruments Ltd. (TTi) is one of Europe’s leading

manufacturers of test and measurement instruments.

Products have been sold under two brand names:

TTi and Aim.

In the future, however, the full product range will be branded Aim-TTi.

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)

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

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.

Product Summary

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Bench and system power supplies from 30 watts up to

1200 watts using linear, mixed-mode and PowerFlex

regulation technologies.

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arbitrary generators, arbitrary/function generators and

pulse generators.

Precision Measurement Instruments

Benchtop DMMs, frequency counters, component

measurement instruments (LCR), electronic dc loads,

current probes.

RF and EMC Test Equipment

Spectrum analyzers, signal generators, frequency counters,

power meters, emc measurement instruments.