At a minimum, you will get a sense of how the facility is wired and what the typical loads are.

3. Interview Affected Personnel and Keep an Incident Log

Interview the people operating the affected equipment. You will get a description of the problem and often turn up unexpected clues. It's also good practice to keep a record of when problems happen and what the symptoms are. This is most important for problems that are intermittent. The goal is to find some pattern that helps correlate the occurrence of the problem in the "victim load" to a simultaneous event elsewhere. Logically, this trouble-logging is the responsibility of the operator closest to the affected equipment.

A Lineup of Power Quality Culprits from Utility Source to Receptacle

Lightning
Can be extremely destructive if proper surge protection is not installed. It also causes sags and undervoltages on the utility line if far away. If close by, it causes swells and overvoltages. But in the final analysis, lightning is an act of nature and not in the same category as the damage man does to himself.

Utility Automatic Breaker Reclosure
Causes short duration sags/outages, but better than the alternative, a longer-term outage.

Utility Capacitor Switching
Causes a high-energy voltage disturbance (looks like an oscillating transient riding on the wave). If the cap bank is near the facility, this transient can propagate all through the building.

Commercial High Rises without Enough Distribution Transformers
Trying to cut corners in the wrong places; running 208 V feeder up twenty storeys is not the road to PQ.

Gensets not Sized for Harmonic Loads
Excessive voltage distortion affects electronic control circuits. If SCR converter loads are present, notching can affect frequency control circuits.

Applying PF Correction Capacitors without Considering the Effects of Harmonics
Harmonics and caps don't mix. Those bulging capacitors are crying for help.

Inrush Currents from High Torque Motor Loads Started Across-the-line
Causes voltage sags if the load is too large or the source impedance too great. Staggered motor starts can help.

Undersized Neutrals at Panel Board
In the era of the 3rd harmonic, neutrals can easily carry as much current or more current than the phase conductor. Keeping them undersized leads to overheated lugs, potential fire hazards and high N-G voltage.

Running Power and Signal Cables Together
Think of the signal cable as a single-wire transformer secondary and the power cable as the primary. The opportunities for coupling are endless.

Loose Conduit Connections and Lack of Green Wire Grounding Conductor
Causes open or high impedance ground circuit. Not good for PQ or safety.

Shared Neutrals on Branch Circuits
Causes load interaction and overloaded neutrals.

Laser Printers and Copiers Sharing Branch Circuits with Sensitive Loads
Guaranteed periodic voltage sags and switching transients.

Miswired Receptacles (N-G Swapped)
Hard to believe, but they are out there in quantity. Guaranteed to put return currents on the ground conductor and create a noisy ground.

Data Cables Connected to Different Ground References at Each End
Ouch! Shows up as voltage between equipment case and the data cable connector.

Hi-frequency Noise
The most effective high frequency grounding technique is the installation of a Signal Reference Grid (SRG).

And in a Class by Themselves
Isolated ground rods (below) They're a safety hazard because the earth is a high impedance path and will prevent enough current from flowing to trip the breaker. They also cause ground loops; after all, every electron still has to go back where it came from. One of the great mysteries of PQ is how some manufacturers can insist that their equipment warranty is void unless an isolated ground rod is installed.

Illegal N-G Bonds
Guaranteed to put return currents on ground. Not only is it a PQ problem, it's a plumbing problem. Circulating ground currents cause corrosion of water pipes.

(Article reprinted under permission of Fluke. In India Sales, Service & Calibration: TTL Technologies Pvt Ltd, Bangalore. Tel: 080-25260646, 25251859. Fax: 91-80-25291285. Email: response@ttlindia.com)

International Safety Standards for Test Tools

*CAT IV product specifications are not yet defined in the standard.

IEC 61010 establishes international safety requirements for low voltage (1000V or less) electrical equipment for measurement, control and laboratory use. The low voltage power distribution system is divided into four categories, based on the proximity to the power source. Within each category are voltage listings--1000V, 600V, 300V, etc.

The key concept to understand is that you should use a meter rated to the highest category, as well as the highest voltage, that you might be working in. For PQ troubleshooters, that means a meter rated to CAT III 600 V or CAT III 1000 V (the specifications for CAT IV have not yet been defined by IEC). We recommend that you do not use CAT II rated meters, scopes or test leads and probes on CAT III circuits. The CAT ratings should be marked near the voltage inputs of the instrument. Meters designed to IEC 348, the previous standard, will typically not meet the more stringent safety specs of IEC 61010 CAT III 600/1000V. IEC 61010 requires increased protection against the hazards of transient overvoltages. Transients can cause an arc-over inside an inadequately protected meter. When that arc-over occurs in a high energy environment, such as a three-phase feeder circuit, the result can be a dangerous arc blast. The potential exists for serious harm to personnel as well as damage to the meter.

Independent Testing and Certification

Manufacturers can self-certify that they meet IEC 61010 specs, but there are obvious pitfalls for the end-user in self-certification. Certification by an independent testing lab provides assurance that the meter meets IEC requirements. Look for a symbol and listing number of an independent testing lab such as UL, CSA, T