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Q: How is ROD-L's arc detection different from that of other manufacturers?
A: ROD-L hipot testers have the capability of detecting arcs as short as 10 microseconds in duration, which greatly increases the ability to catch faults that could eventually grow into severe electrical hazards.
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Q: Is hipot testing dangerous?
A: Yes! It is inherently dangerous because of the high voltage and high currents involved. ROD-L units have several safety features built-in to eliminate operator hazard in normal testing, such as; 2 millisecond shutdown time upon detection of failure, 10 microsecond arc detection, a ground-sense circuit which ensures that there is always an escape path for current in the event of catastrophic device-under-test failure, rapid discharge of stored charge in the device-under-test at the end of every test cycle.
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Q: Why doesn't ROD-L offer hipot testers that supply both AC and DC voltage in the same box?
A: None of the regulatory agencies require that a product be tested with both AC and DC voltages. They do, however, generally offer a choice of testing a product with AC at a given voltage or with DC at a different voltage (typically 1.414 times higher than the AC value). The potential problem with using one hipot tester that offers both AC and DC in the same box is operator error. The wrong voltage type (and therefore wrong voltage level) could be inadvertently selected by the operator, and by the time the error is discovered, it may be too late; the products may have already been shipped. Also, the proximity of the different types of transformers and other major components inside one small cabinet that would be necessary would reduce the reliability of the hipot tester.
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Q: How safe are ROD-L units compared to those of other manufacturers?
A: The combined multi-level safety features of ROD-L units make them the very safest units on the market.
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Q: How often should the units be calibrated?
A: At least once a year, which is the minimum required by the regulatory agencies such as UL. However, units that are in constant operation more than one shift per day, five days per week should be calibrated every six months. Note also that ROD-L manufactures the ML11 and ML12 Test Load boxes for daily (UL required!) pre-shift functional checks of the hipot and ground continuity testers.
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Q: Why can't I just use an outside calibration house or perform my own annual calibration?
A: You could do that, however, have ROD-L perform the calibration offers a number of advantages; 1) All necessary repairs are included at no additional cost, 2) ROD-L technicians are very experienced with the units and can even perform preventive maintenance and prevent units from malfunctioning and prevent your loss of production time, 3) Quick turnaround--even 24 hour turnaround upon request for a small additional fee, 4) All work is fully guaranteed for a year, so that calibration at ROD-L annually means that you would never have to pay for repairs.
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Q: Is hipot testing destructive to my product?
A: No. When properly performed, hipot testing will not damage the device-under-test. The only purpose of the hipot test is to measure the strength of the insulating material that isolates the user-accessible parts of the device-under-test from its active circuitry. The active circuitry itself is not being driven during the test, unless there is a major internal wiring flaw inside the product being tested that could cause this. But even in this worst-case scenario all ROD-L units are designed to shut down within 2 milliseconds of a detected failure.
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Q: Is the arc sensitivity level adjustable?
A: No! ROD-L determined more than 25 years ago, using internal company research as well as industry research, that arcs as short as 10 microseconds in duration are indicative of product defects that will likely lead to product safety failures within the expected life of most products. Arcs of shorter duration than 10 microseconds have been determined to be, in all likelihood, noise or corona discharge related, and therefore not indicative of product defects. If a manufacturer were using a hipot tester that had adjustable arc sensitivity, two problems could immediately arise; 1) the operator could inadvertently select the wrong level, potentially invalidating this critical product safety measure and putting your company at great potential liability, 2) the manufacturer could decide, for convenience sake, to use a less stringent arc sensitivity level and therefore reject less products, but at the cost of putting inherently unsafe products in the hands of customers--again exposing the manufacturer to potential product liability lawsuits.
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Q: How can I justify the cost of a ROD-L unit to do such simple tests?
A: Safety--protection of the test personnel in your company, Liability Protection--detecting faults that could injure your customers before your products leave your facility, Quality--detecting the potential failures that could impact your product's performance in the field before the products leave your facility. Money invested in good test equipment now will save you much more money down the road.
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Q: How difficult is it to perform a hipot test?
A: It is actually not that difficult to perform the test. If the product being tested has a 3-prong power cord, you only need to plug it in to the front panel of the hipot tester and then connect the chassis ground sense wire from the post on the front of the hipot to an external metal portion of your product. The green ready light should then immediately illuminate, after which you would push the "start" button. (See the "Quick Start" guides on our website.) For products that do not have a 3 prong power cord, you essentially just need to use 2 alligator clips--one for HV out and the other for HV return to connect your product to the hipot tester.
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Q: My product has a 2-prong power cord. Can I still perform a hipot test?
A: Yes. There is a special set-up diagram in the back of all of our users manuals for connecting products with 2-prong power cords.
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Q: Can ROD-L Hipot Testers be interfaced with ROD-L Ground Continuity Testers?
A: Yes. Essentially, ROD-L units are designed so that every model should be able to interface with every other model. The Ground Continuity Testers come with interface and jumper cables to allow connection to the Hipot Testers. Once the two are connected together you would only need to make one test connection to your product and push the start button once to cause both tests to be performed in sequence, as though they were one unit.
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Q: What is the difference between the AVS5 models and the BVS5 models?
A: The BVS5 models offer the additional feature of being able to give a reading for the 'real' current (resistive current).
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Q: What kind of warranty does ROD-L offer?
A: All ROD-L products are covered by a five-year warranty. However, in addition to this, if you send your units to us at least once a year for complete calibration, we will repair any problem the unit may have at no additional cost. This gives you practically a lifetime warranty on the units*
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Q: Where should I set my trip currents?
A: There is no regulatory agency standard for this, primarily because of the great variety of designs and materials by every manufacturer in every industry. Different amounts of current will be drawn in normal construction of any product, from manufacturer to manufacturer. So we recommend that an initial test sample of known good products be drawn (probably at least 32 pieces for a good statistical sample). From the distribution of current readings at the required hipot test voltage for that class of product, an upper limit can be determined--maybe at a 6 sigma or 8 sigma point, which will become the trip current limit. This same method could be used for determining a 'real' current trip point although most manufacturers do not have a test requirement for this parameter. The 'real' current is, however, an excellent diagnostic tool. The undercurrent function is generally only used to verify that the power switch on the device-under-test is in the "on" position. The same method could also be used to determine its setting, or an arbitrary setting of 1 or 2 on the vernier dial could be used as more of a "go/no-go" type test. Otherwise we recommend that the undercurrent pot be set to zero.
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Q: What are the factory settings for the trip currents?
A: Unless otherwise requested by the customer, the total current is set to the maximum (10 on the vernier dial which equals 100% of the unit max), the 'real' current is also set to the maximum, and the undercurrent is set to the minimum (0 on the vernier dial).
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Q: What is the difference between the 'real' current and the total current?
A: The 'real' current is that portion of the total current which excludes capacitive current flow. Essentially it is the resistive portion of the total current, sometimes referred to as the 'true leakage current'. Typically this is about 10% of the current drawn on most products during a hipot test (unless you are testing resistors in which case it would be 100%!). The total current is the 'real' current plus the current flowing through capacitive pathways.
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Q: What is the difference between the ML11 and the ML12 Test Load Boxes?
A: The ML11 consists of a fixed capacitive load, while the ML12 consists of a fixed resistive load. Basically either type can be used on any ROD-L unit, but note that the M100DC units, because they supply a purely DC waveform, will not show any current with the ML11 boxes. The "fail" posts on the ML11 and ML12 boxes are floating points.
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Q: I need a hipot tester which can set the voltage to various values. What model should I order?
A: Normally the variac knob on the rear panel of the M100/M500 units, or the potentiometer on the rear panel of the M100DCs, allows the user to adjust the voltage from 0 up to the maximum voltage output level of his particular unit. For users that need up to 6 discreet settings, we have an option which can be installed which provides 5 hard-wired settings with the sixth remaining user-adjustable.
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Q: ROD-L units appear to cost more than other manufacturers' units. Why should I buy ROD-L units when I can buy cheaper ones?
A: ROD-L units offer a number of advantages over all other manufacturers;
1) Safety -- ROD-L units have multiple levels of safety features built-in to protect the operator, far exceeding regulatory agency requirements, such as the 2-millisecond shutdown time after detection of failures. ROD-L has won the Consumer Product Safety Award from the Professional Insurance Agents Association. 2) Overall cost savings -- An employee injured performing any hipot-type test or a customer of yours injured by your product in the field would mean a major liability loss, if it were determined that your electrical product safety testing were not done to the industry-high standard that ROD-L units offer. ROD-L units in this sense are like almost like an insurance policy. Also, consider the cost of having to recall your products from the field if a serious defect is discovered that could have been detected by the 10-microsecond arc detection capability of ROD-L units. 3) Quality -- The accuracy, repeatability, and reliability that ROD-L units offer above other brands of hipot testers will allow you to perform better testing of your products before they leave your facility. This means higher product quality for you and better sales in the long run. Consider also the longevity factor; ROD-L units last a very long time in the field, as the failure rate for the major internal components is extremely low.
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