DLRO10_DLRO10X_DS_en_V10.qxp DLRO10HDX User Manual Brochure

User Manual: DLRO10HDX-User-Manual-Brochure

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NEW DLRO10HD GIVES YOU THE POWER

INTRODUCTION

Megger has been manufacturing low resistance ohm meters

for many years. In fact the first Low resistance ohmmeter

was launched in 1908. The first low resistance ohm meter,

launched under the DUCTER trade mark was developed by

Evershed and Vignoles (one of the companies that evolved

into Megger) and used a cross-coils meter movement.

Today, Megger has a comprehensive range of Digital Low

Resistance Ohmmeters, under the DLRO trade mark,

providing accurate and reliable measurements with test

currents ranging from a few µA to 600 A suitable for many

applications.

The DLRO10HD is the latest addition to the Megger range

fulfilling the requirement for a heavy duty instrument in

both test specification and physical toughness.

What Power can the DLRO10HD provide?

When discussing “power” with regard to a DLRO we could

be talking about one of two things. The DLRO10HD has spe-

cial features in both of these departments, each proving real

benefits to the user.

■PPoowweerr ssuuppppllyy– the DLRO10HD like many low resis-

tance ohmmeters is powered by rechargeable batteries.

However, what happens when the battery is flat? The

result is a few hours waiting for the battery to charge!

The DLRO10HD can be operated from a mains or line

supply and charge its battery at the same time. No more

waiting for a battery to charge. This is particularly useful

in manufacturing environments.

■PPoowweerr oouuttppuutt– applying too much current during a

test will result in power dissipation in the test piece, in

turn resulting in heating. The heating alters the resis-

tance of the test piece. This is the very reason why the

established DLRO10 limits power output to 0.2 W.

However there are some applications where having

higher power output is useful. The new DLRO10HD is

unique in that it gives you the best of both worlds. The

user can select measurement ranges of either low or high

power.

The DLRO10HD features two ranges with extended compli-

ance. Effectively there are two 2.5 Ωand two 250 mΩranges

one low power, and one high power. The chart below shows

the power output curves for the two 250 mΩranges. Each

range provided 10 µΩresolution allowing the user to make

comparative measurements at either 0.25 Ωor 25 Ωmaxi-

mum outputs.

DLRO10HD

10 A Digital Low Resistance Ohmmeter

■What Power can the DLRO10HD provide?

■Why does the DLRO10HD let you choose

the power output?

■DLRO10HD Test range selection?

■What are the applications for the

DLRO10HD?

■What other advantages does the

DLRO10HD offer?

■What other <10 A instruments are in the

range?

DLRO10HD 250mΩ Ra nges

High Power and Low Power Output Comparison

0.0025W Max

25.0W Max

0.000001

0.00001

0.0001

0.001

0.01

0.1

1

10

100

0 0.05 0.1 0.15 0.2 0.25

Resista nce

Power (W)

Low Power

250mΩ Ra nge

High Pow er

250mΩ Ra nge

DLRO10HD

10 A Digital Low Resistance Ohmmeter

Why does the DLRO10HD let you choose the

power output?

Here are three examples that will help to explain:

■CCoonnttaammiinnaattiioonn– The application of high power will

result in test piece heating. However there is another

aspect to this. Many tests are performed on bonds,

connections, contacts etc. used in low current appli-

cations. If you have contamination between surfaces,

higher test current and power will just “blast” through

the contamination. This results in a good test result,

even though in use the connection will prove to be un-

reliable. Testing at a low current and power will show up

the problem much more readily.

■RRoouugghh ssuurrffaacceess– An example where high power is an

advantage is testing connections, or bonds with rough

surfaces. In some cases a good test result will be

obtained with a low test current and power, the contact

points between contact surfaces being of low enough

resistance. However applying a higher test current and

power will heat these small points of contact. The result

is a test result changing as the heating takes place, high

lighting the problem.

■FFrraayyeedd wwiirreess– On lower current carrying systems

(typically less than 10 A) testing with higher power will

cause heating on weaknesses such as frayed wired. The

remaining wires presenting a higher resistance.

DLRO10HD Range selection

The selection of the ranges on the DLRO10HD couldn’t be

simpler. The colour coded rotary range switch gives simple

indication of resistance measurement range and test current

selected. The yellow band contains the test current. The

green ranges indicate ranges where the output power is

limited to 0.25 W, and the red ranges indicate the high

power ranges that will dissipate up to 25 W into the test

piece.

The 25 W power output can be supplied continuously for at

least 60 seconds. This means resistance with inductance can

be measured. However it must be stressed that the

DLRO10HD is not suitable for testing large inductive cir-

cuits, such as power transformers.

In addition in normal (non inductive) applications this

affords the instrument an excellent duty cycle so the user

will not spend excessive amounts of time waiting for the

instrument to cool between tests.

What are the applications for the DLRO10HD?

As with many low resistance ohm meters the applications

are far and wide. Here are a few applications suited to a

DLRO10HD.

■During electrical manufacturing processes

■TTeessttiinngg sswwiittcchheess,, ccoonnnneeccttoorrss aanndd rreellaayyss– To

ensure contact resistance is within specified values.

■CCaabbllee rreessiissttaannccee– too low means too much copper

in cable (higher costs), too high means not enough

copper (cables’ current carrying capacity com-

promised)

■MMoottoorrss– To determine heat rise under load, measure

winding resistance, check for short circuits or open

circuits.

■GGeenneerraattoorrss- To determine heat rise under load,

measure winding resistance, check for short circuits or

open circuits.

■FFuusseess- To ensure resistance is within specified values.

■CCaabbllee lloooommss– Checking bonding and inter-

connections when installing in equipment, racks etc.

■UUPPSS // CCaarr bbaatttteerriieess- Carrier to plate weld

resistance, high resistance indicates poor weld quality

that will restrict battery’s ability to carry current.

■AAiirrccrraafftt aasssseemmbbllyy aanndd mmaaiinntteennaannccee

■MMaaiinn ffrraammee eelleeccttrriiccaall aanndd mmeecchhaanniiccaall bboonnddss–

to ensure a stable “ground plan” to protect aircraft

from static electricity and lightning strikes.

■Static wick bonding

■Antenna bonds

■Control linkage bonding

■Battery connection and interconnection

■Integrity of structure and exhaust system

■Metallic coating resistance

■RRaaiillwwaayy // RRaaiillrrooaadd IInndduussttrryy

■SSttrraapp aanndd wwiirree bboonndd bbeettwweeeenn rraaiill sseeggmmeennttss–

maintaining performance of control and telephone

system. Minimising power loss on three rail systems.

However sometime higher test currents are specified.

■CCaabbllee jjooiinnttss– power system efficiency.

■Eaarrtthh // ggrroouunndd bboonnddss– e.g. lightning protection on

structures. Ground mats, ground conductor rings,

metal cladding, metal ceilings, metal floors, hand rails,

seats etc. to limit step and touch potential.

■Pllaattffoorrmm eeddggee ddoooorrss– Earth / ground bonding

(mainly underground systems)

■AAlluummiinniiuumm rreeffiinneerriieess

■GGrraapphhiittee eelleeccttrrooddeess– to verify density

■SShhiipp bbuuiillddiinngg oorr aannyy mmeettaall ssttrruuccttuurreess

■WWeelldd qquuaalliittyy– measure at regular intervals along

weld length looking for uniformity.

■IInnssttaalllleedd eeqquuiippmmeenntt bboonnddss– to steel structure /

hull.

■RRaaww mmaatteerriiaall pprroocceessssiinngg, e.g. cement plants

■PPoowweerr ccaarrrryyiinngg eelleemmeennttss– installation and

maintenance

■GGrroouunndd bboonnddss- cement is corrosive

DLRO10HD

10 A Digital Low Resistance Ohmmeter

■Automotive industry

■CCaabbllee lleeaaddss iinn rroobboott ssppoott wweellddeerrsswork-harden

through flexing causing strands to break. Results in

poor weld quality.

■PPoowweerr GGeenneerraattiioonn aanndd DDiissttrriibbuuttiioonn

■BBuuss bbaarrss– lap joint tests to maintain low resistance,

and hence maintaining efficiency and reducing likely

hood of fire.

■CCaabbllee jjooiinnttss– including overhead lines. High imped

ance joint can explode.

■FFuusseess– connections

■UUnniinntteerrrruuppttiibbllee PPoowweerr SSuuppppllyy ((UUPPSS))

■BBaatttteerryy ssttrraappss– quality of connections. Preventing

potential of fire and failure to operate

■CCaarrrriieerr ttoo ppllaattee wweelldd rreessiissttaannccee– High resistance

indi cates poor weld quality that will restrict battery’s

ability to carry current.

■Military vehicles – Trucks, tanks etc.

■Innssttaalllleedd eeqquuiippmmeenntt ssuucchh aass rraaddiioo eeqquuiippmmeenntt-

ground bonding to vehicle chassis.

■BBuuiillddiinnggss –– wwiirriinngg,, lliigghhttnniinngg pprrootteeccttiioonn bboonnddss

■VVaarriioouuss bboonndd,, bbootthh ffoorr ppoowweerr ddiissttrriibbuuttiioonn aanndd

eeaarrtthh ggrroouunnddiinngg– check for step and touch voltage

safety in fault condition.

■CCoonndduuiitt ccoonnttiinnuuiittyy– metal conduit, detect

corroded or loose threads etc.

■PPiippee lliinneess

■CCaatthhooddiicc pprrootteeccttiioonn– check connection etc. Tough

environment ideal for the DLRO10HD

■WWiinndd ttuurrbbiinneess

■LLiigghhttnniinngg pprrootteeccttiioonn – wing tip to base, or

component parts in manufacture. Long test leads

available for this application.

■EEaarrtthh ggrroouunndd bboonnddss– various

What other advantages does the DLRO10HD

offer?

The DLRO10HD is a heavy duty instrument designed to

operate in the toughest of conditions. Below is a complete

list of the key ffeeaattuurreess aanndd bbeenneeffiittss:

■BBootthh hhiigghh aanndd llooww ppoowweerr oouuttppuuttss

■DDiiaaggnnoossttiicc ttooooll. Low power to identify problems

such as bond contamination and corrosion. High

power to show up weaknesses due to heating.

■HHiigghh ppoowweerr ((1100 AA iinnttoo 225500 mm

Ω

,, oorr 11 AA iinnttoo

22..55

Ω

mmeeaassuurreemmeennttss)) wwiitthh iinndduuccttiivvee mmooddee

■Will pass 10 A continuously for at least 60 seconds

■Less time waiting for unit to cool

■OOppeerraatteess ffrroomm mmaaiinnss aass wweellll aass hhiigghh ccaappaacciittyy

lleeaadd aacciidd bbaatttteerryy

■AAllwwaayyss rreeaaddyy ttoo tteesstt, even with a flat battery

■HHiigghh lleevveell ooff iinnppuutt pprrootteeccttiioonn,, 660000 VV wwiitthhoouutt

ddaammaaggee ((CCAATT IIIIII 330000VV rraatteedd wwiitthh DDHH77 iinnssuullaatteedd

tteerrmmiinnaall ccoovveerriinngg lleeaaddss))

■Inadvertent connection to mains / line supply will

not damage instrument or blow fuse. Instrument

will continue to operate as normal. Particularly useful

when testing UPS battery straps.

■AAuuttoommaattiicc tteessttiinngg

■Initiates test on contact, passes current in each

direction in 3 seconds to cancel out the effect of

thermal E.M.F. caused by contact between dissimilar

metals.

■SSiimmppllee ooppeerraattiioonn aanndd ffaasstt tteessttiinngg

■Time is money, no time wasted reading complicated

user guides and short test time saves time.

■TToouugghh hhoouussiinngg IIPP6655 lliidd cclloosseedd,, IIPP5544 iinn

ooppeerraattiioonn

■Ideal for very tough conditions both indoor and out

side

UK

Archcliffe Road Dover

CT17 9EN England

T +44 (0) 1304 502101

F +44 (0) 1304 207342

UNITED STATES

4271 Bronze Way

Dallas TX 75237-1088 USA

T 800 723 2861 (USA only)

T +1 214 333 3201

F +1 214 331 7399

OTHER TECHNICAL SALES OFFICES

Norristown USA, Sydney AUSTRALIA,

Toronto CANADA, Trappes FRANCE,

Kingdom of BAHRAIN, Mumbai INDIA,

Johannesburg SOUTH AFRICA and

Conjure THAILAND.

Registered to ISO 9001:2000 Cert. no. Q 09290

Registered to ISO 14001-1996 Cert. no. EMS 61597

DLRO10HD_AN_en_V01

www.megger.com

Megger is a registered trademark

What other <10A instruments are in the range?

Megger also manufacture two other DLRO instruments, the DLRO10 and DLRO10X. Both these instruments offer light

weight, hang around the neck operation with 0.2 W limited power output.

Full information on these and any other Megger products can be found on www.megger.com

More comprehensive information on understanding and measuring low resistance can be found in the Megger publication “A

Guide to Low Resistance Testing”.

DLRO10HD

10 A Digital Low Resistance Ohmmeter

Feature DLRO10 DLRO10HD DLR010X Benefit/s

Power limied ouput Negligible heating, little need for contact

test ranges (<0.25 W) ■■ ■temperature compensation

Can help to highlight contamination

Extends battery life

High power output Can help to highlight weakness with heating, such

test ranges (25 W) ■as poor connection due to rough surfaces or

broken strands on cables

Improved inductive load performance

Auto current reversal ■■ ■Cancels out thermal EMFs

Auto start

(continuity detection) ■■ ■Fast operation without pressing test button

Inadvertent connection to live line supply or

High input protection <600 V ■■ ■UPS voltage will not even blow a fuse

Testing just continues as normal

Noise immunity specified at Make measurement in harsh environments

100 mV ■■ ■

Noise limit exceeded indicator ■Confidence that measurements are not effected

User interchangeable detachable Continuous testing with optional second battery.

battery pack ■■Use one battery while second charges

Hang from neck operation ■■Ideal for use up ladders and platforms improved

manoeuvrability

Operate from mains/line supply Continuous testing from mains ideal for

manufacturing applications

■Always ready to test no waiting for battery to

charge

IP65 lid closed ■Can be transported in any wet conditions

IP54 in use ■Can be operated in the rain

Ultra tough case ■Built to take the knocks in the most arduous of

conditions

Test result storage with memos Ideal for predictive maintenance systems

■Less errors in writing down test results

Printer and PC output ■Save results to your PC or send to a printer

User selectable test limits ■Aids rapid testing to specified limits

DLRO10X

DLRO10HD

DLRO10