Electrical Test & Measurement · Electrical Safety Testers
Bench safety compliance analyser combining AC and DC withstand, insulation resistance and, on the top model, ground bond testing, with stored programs and a matrix scanner interface.
7440 (4 models) ·
A single safety analyser is bought for a reason that is rarely written on a specification sheet: the product under test should not have to be unplugged, moved and re-connected between three instruments. The value of a combined unit is the sequence it can run without an operator in the middle of it.
Four models sit in one body. The top model runs an alternating withstand test, a direct withstand test, an insulation resistance test and a ground bond test. The other three drop the bond output and keep the rest, and two of them cap the alternating leakage current at a lower figure than the other two.
The controls are arranged for sequence entry rather than for a single measurement: function keys down the left of the keypad select the test, a numeric block enters the values, and the display shows the step, the setpoint and the measured value together. The rear panel carries the high voltage output, the scanner connections, a serial port, the remote control connector and an input for a barcode reader.
Each function applies a quantity and judges the response. In the alternating withstand test a sine wave is raised over a programmed rise time to the set voltage and held for the test time, while the current through the item is compared with an upper and a lower limit. Exceeding the upper limit is a breakdown; falling below the lower limit usually means the item is not connected. The direct test does the same with a rectified output, and the ripple figure is quoted at full load because that is where it is worst.
Insulation resistance is measured at a lower direct voltage, and the reading is taken after a delay because the current through good insulation keeps falling for a while after the voltage is applied. The material specifies the accuracy in two bands, above and below the middle of the voltage range, which reflects that behaviour rather than a change in the instrument.
The bond test is a different measurement in the same box. A low alternating voltage drives a heavy current through the protective conductor, the drop across it is measured, and the resistance is derived and compared with limits that change with the current segment. A zeroing step removes the resistance of the leads first, which matters because on a bond of a few milliohms the leads can be the larger part of the reading.
The first question is whether a bond test is required at all. It is the only function that separates the top model from the rest, and it cannot be added later, so a product standard that calls for it decides the model outright.
The second is the leakage ceiling. Two models stop at the lower figure and two reach the higher one, and the figure has to come from the product standard rather than from a preference for headroom.
The third is the fixture. A product with several test points is impractical to test one lead at a time, and the scanner interface is what turns the instrument into a sequencer. Count the points before choosing the scanner, and remember that one scanner is already inside the instrument.
The fourth is how programs are recalled. Fifty groups with a name stored against each is enough for a varied bench, but if operators select by product label, the barcode input at the rear is the feature that decides the configuration.
The instrument judges against limits; it does not characterise insulation. Where the breakdown voltage itself is the quantity of interest, a tester with a ramped output and a recorded curve is the right instrument, and a pass or fail unit will only report that breakdown happened somewhere above the limit.
Leakage measurement includes everything connected across the output, including the fixture, the scanner and the leads. On a product with very low leakage that residual current can be a large fraction of the reading, which is why the lower limit has to be set with the fixture in place and characterised, not on an open bench.
The bond function belongs to one model only, and its current is capped at a figure that may be below what a particular standard asks for. The material mentions a higher current on request, which means the requirement has to be raised at the order stage rather than assumed from the model table.
Finally, combining functions in one box means one failure stops the sequence. That is usually what a production test wants, but a laboratory that needs to investigate which test failed, and by how much, may prefer separate instruments with independent records.
Every value below is taken from source documentation. Where a parameter is not stated in the available material it is marked as information required rather than estimated.
| Output voltage | 0 to 5 kV, resolution 1 V, ±(1% of setting + 5 V)Standard |
|---|---|
| Output frequency | 50 or 60 Hz, selectable, ±100 ppmStandard |
| Regulation | ±(1% of setting + 5 V) from no load to full loadStandard |
| Waveform | Sine, total harmonic distortion below 2% into a resistive load, crest factor 1.3 to 1.5Standard |
| Upper leakage limit | 0.00 to 40.00 mA on 7440 and 7430; 0.00 to 30.00 mA on 7420 and 7410; ±(2% of setting + 3 counts)Standard |
| Lower leakage limit | 0.000 to 9.999 mA, resolution 0.001 mA, ±(2% of setting + 3 counts)Standard |
| Rise time | 0.1 to 999.9 s, resolution 0.1 s, ±(0.1% + 0.05 s)Standard |
| Test time | 0.3 to 999.9 s (0 = continuous), resolution 0.1 s, ±(0.1% + 0.05 s)Standard |
| Arc detection | 1 to 9, with 9 the highest sensitivityStandard |
| Test lead zeroing | 0 to 200 mA, manual or automatic, as printedStandard |
| Voltage display range | 0.00 to 6.00 kV, resolution 1 V, ±(2% of setting + 5 V)Standard |
|---|---|
| Ripple | Below 5%, measured at 6 kV into a 9999 μA resistive loadStandard |
| Upper leakage limit | 0.000 to 9999 μA, resolution 0.1 μA, ±(2% of setting + 3 counts)Standard |
| Lower leakage limit | 0.0 to 9999 μA, resolution 0.1 μA, ±(2% of setting + 3 counts)Standard |
| Rise time | 0.1 to 999.9 s, resolution 0.1 s, ±(0.1% + 0.05 s)Standard |
| Test time | 0.4 to 999.9 s (0 = continuous), resolution 0.1 s, ±(0.1% + 0.05 s)Standard |
| Arc detection | 1 to 9, with 9 the highest sensitivityStandard |
| Output voltage | 100 to 1000 V DC, resolution 1 V, ±(1% of setting + 3 V)Standard |
|---|---|
| Resistance resolution | 1 MΩStandard |
| Accuracy at 500 to 1000 V, 1 to 1000 MΩ | ±(2% of setting + 2 counts)Standard |
| Accuracy at 500 to 1000 V, 1000 to 9999 MΩ | ±(8% of setting + 2 counts)Standard |
| Accuracy at 100 to 500 V, 1 to 1000 MΩ | ±(8% of setting + 2 counts)Standard |
| Upper limit | 0 to 9999 MΩ, where 0 switches the judgement offStandard |
| Lower limit | 1 to 9999 MΩStandard |
| Judgement delay | 0.5 to 999.9 s (0 = continuous judging), resolution 0.1 sStandard |
| Charging current lower limit | 0.000 to 3.500 μA, or set automaticallyStandard |
| Output voltage | 3 to 8 V AC, resolution 0.01 V, ±(2% of reading + 3 counts) measured open circuitStandard |
|---|---|
| Output frequency | 50 or 60 Hz, selectable, ±100 ppmStandard |
| Output current | 3.00 to 30 A AC, 0.01 A steps, ±(2% of setting + 3 counts); 40 A on requestStandard |
| Resistance range | 0 to 600 mΩ, resolution 1 mΩ, ±(2% of setting + 2 counts)Standard |
| Upper and lower limits | 0 to 600 mΩ over 3 to 10 A; 0 to 150 mΩ over 15 to 30 A; resolution 1 mΩStandard |
| Test time | 0.5 to 999.9 s (0 = continuous), resolution 0.1 s, ±(0.1% + 0.05 s)Standard |
| Lead zero compensation | 200 mΩ maximum, resolution 1 mΩ, ±(1% of setting + 1 mΩ)Standard |
| Program memory | 50 groups, each with eight steps, each group named for a productStandard |
|---|---|
| Display | 20 × 2 cm dot matrix OLEDStandard |
| Display brightness | Nine steps, set from the keypadStandard |
| Buzzer volume | Ten steps, where 0 switches it offStandard |
| Keyboard lock | Four-digit numeric passwordStandard |
| Remote input | Test and resetStandard |
| Remote output | Pass, fail and processingStandard |
| Serial interface | RS232Standard |
| Matrix scanner | One built in; two scanners in total can be connectedStandard |
| Optional scanners | H.V × 4 and H.V × 8Optional |
| Calibration | Software calibration entered from the panel keysStandard |
| Input supply | 115 or 230 V AC ±15%, single phase, selectableStandard |
|---|---|
| Input frequency | 47 to 63 HzStandard |
| Input fuse | 6.3 A as printed, with a 5.0 A figure also visible on the drawingStandard |
| Dimensions | 432 × 147 × 500 mm and 432 × 147 × 300 mm, not bound to individual modelsStandard |
| Weight | 22 kg, 22 kg, 18 kg and 12 kg listed without a model allocationStandard |
| Operating environment | 0 to 40 °C, 20 to 80% RHStandard |
| Standard accessory | Insulation test lead, listed for the 74 seriesStandard |
| Calibration certificate | Not stated in the materialInformation required |
| Ingress protection | Not stated in the materialInformation required |
| Model | Configuration | Key ranges | Availability |
|---|---|---|---|
| 7440 | AC and DC withstand, insulation and ground bond | AC to 40 mA, DC to 9999 μA, insulation to 9999 MΩ, bond to 600 mΩ | The only model with the ground bond function |
| 7430 | AC and DC withstand with insulation | AC to 40 mA, DC to 9999 μA, insulation to 9999 MΩ | No ground bond function |
| 7420 | AC and DC withstand with insulation | AC to 30 mA, DC to 9999 μA, insulation to 9999 MΩ | Lower AC leakage ceiling than 7430 |
| 7410 | AC and DC withstand with insulation | AC to 30 mA, DC to 9999 μA, insulation to 9999 MΩ | Listed with the same figures as 7420 |
Certifications are only published once a certificate copy can be produced, so this section is deliberately empty rather than populated with assumed approvals. Tell us which approvals your application requires and we will confirm what is available for this instrument.
The following are required for a complete specification but are not stated in the documentation supplied to us. They are listed rather than estimated:
Only if the product has a protective conductor that has to be checked for continuity at a defined current. The other three models run the withstand and insulation tests but have no bond output at all, so a bond test would have to be done on a separate instrument. If the product standard calls for a bond test, the choice is made for you.
The material gives them the same figures in every column, including the alternating leakage ceiling, and does not explain the distinction. Treat the two as the same specification until the supplier confirms what separates them, and specify by the figure your standard requires rather than by model number alone.
Yes, through the matrix scanner. One scanner is built into the instrument and a second can be connected, and the scanners are offered in four-channel and eight-channel form. The instrument steps through the points in the stored sequence, which is what makes a multi-point harness practical on a single bench.
Whether a bond test is required, which decides between the top model and the others; the leakage ceiling the product standard allows; how many test points the fixture has, which sets the scanner requirement; and whether programs have to be selected from a barcode, since that needs the scanner interface at the rear.
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