Ventex Tech - Troubleshooting Guide

Ventex Generation III UL 2161 LISTED electronic power supplies are different.
With the growing number of electronic power supplies being used in the sign industry and adoption of the UL2161 standard, sign builders will encounter some new situations. The following are guidelines to make the features and installation of Ventex VT series power supplies easier to understand. Using this information and following these suggestions during installation will help eliminate possible long or short-term problems.

What is UL 2161?
UL 2161 is a standard created by UL to address the change in the 1996 National Electric Code. This standard requires electronic power supplies, with secondary output greater than 2000V to ground, to have secondary ground fault protection. This is now a requirement in UL 48.

How does this affect an electronic power supply?
Previously, if electronic power supplies had secondary ground fault protection, the “trip point” was 25-35 mA to ground. To be UL 2161 LISTED, that “trip point” is now a maximum of 15 mA to ground. This “reduced trip point”, along with capacitance coupling, could make all electronic neon power supplies seem more sensitive than products that you have used in the past.

What is capacitance coupling?
Capacitance Coupling results from the electric field that surrounds every AC current carrying conductor, such as GTO cable or neon tubes. It has the ability to conduct AC current through air between the tubes, GTO, electronic power supply and any mounting surface. This can rob current (mA) from the tubes resulting in a loss of brightness, cause over loading of the power supply or result in false tripping. These effects increase with the voltage increases.

If you have ever seen an unpowered tube glow while sitting next to tubes or GTO powered by an electronic transformer, that is an example of capacitance coupling. Stray capacitive current from the lit circuit is exciting the non-energized tube. Another example includes the dimming or tripping of a lit tube when you grasp it with your hand. When this happens, you are actually drawing current from power supply by capacitance coupling.

All signs have an “effective” ground plane. This could be the “can” of a channel letter or the wall, window or even Plexiglas that exposed neon tubes are mounted on. These ground planes are in effect electrical conductors. Any high voltage wiring, as well as neon tubes in the sign will have capacitance coupling to ground. In extreme cases this can cause neon power supplies with GFI to “trip” due to excess ground fault current or over loading.

• Over Loading - Some electric power supplies on the market can deliver currents or voltages in excess of the rated values when loaded with stray capacitance. This will result in over-heating and can cause premature failure of the unit. Ventex’s VT series incorporates a unique design which controls the current to prevent this.

• Electronic Cross Talk can occur between power supplies, tubes, or GTO leads in multi-transformer applications. If the tubes or GTO leads on different power supplies are close, you may have a sign that will not light unless the power supplies are turned on in a specific order. If the power supplies are placed too close together, power supply overheating or overloading can occur.

• False Tripping is a major problem caused by excessive capacitance coupling. Ventex VT series power supplies have patented circuitry to help eliminate most false tripping. How can I minimize the effects of capacitance coupling? Maximize the distance between tubes, GTO leads, cans, ground planes, etc. Ventex recommends the GTO wire and glass tubes be 1.5” from any surface or ground plane. While this is not always possible or practical, any separation is better than direct contact with any surface. GTO Sleeving will increase the GTO electrical insulation, but will not reduce capacitance coupling. In fact, it may even increase it. A key thought to remember which will help; Always treat the GTO wires with the same respect you treat the neon tubes!

All Ventex units starting approximately June, 2002 incorporate the latest Generation III technology to make these units the most user friendly available. This new technology provides the following.

1. Brown-Out Protection: Eliminates false trip shut down due to low input voltage. At extreme low voltages, the unit may not light the neon tube but will re-strike when the voltage recovers.

2. Surge Protection: Internally clamps input voltage spikes to prevent damage to the neon power supply (this is available on Outdoor CL units only)

3. “Triple Shot” Starting: Automatically will attempt to start or restart up to three times for intermittent problems to resist spurious false trips. You will see up to three “flashes” of light at the home-run electrodes when this occurs.

1. Do Not run GTO leads from any electronic power supply in metallic conduit. If this is done, you will experience severe loss of driving distance and brightness, suffer GTO failure and possible false tripping.

2. Do Not load Ventex VT series power supplies with a mA meter or use a primary side dimmer. The VT series maintains 30 ma output regardless of load or primary voltage.

3. Do Not over load. The VT Series has protection and will “trip” if there is an over load of glass and/or excessive capacitance coupling.

4. Keep GTO leads, particularly “Home Run” wires as short and as far from each other and all surfaces as possible. Ventex recommends 1.5 inches as a minimum if possible.

5. If a high voltage GTO cable has to be run through a thin sheet metal wall, special care must be taken. The sharp edge of a hole could cause rapid deterioration of the GTO cable. This can eventually cause a ground fault condition and “tripping”. Use the largest diameter hole possible and always use an approved bushing to center the cable in the hole.

6. If long jumper leads must be used, place these as close to the middle of the glass run as possible. The voltage and capacitive current will be lower closer to the middle of the sign, which will lessen the chance of over loading or tripping.

7. If leads have to cross, try to space them as far apart as possible and cross them at right angles.

8. Maintain as much space as possible between multiple power supplies, their tubes and wiring. This will minimize the effects of “electronic cross talk.”

9. Balance glass load and “homeruns” as much as possible. This will minimize the chance of tripping.

10. In all signs it is best to wire from the “inside out”. This minimizes current loss due to capacitance coupling through the GTO and the chance of over loading and “tripping”.

11. Dedicated Primary Circuits (Outdoor Application) Ground Fault Protected Units (UL 2161 Listed) require a dedicated circuit for proper operation. NEC Section 600.5(A) disallows any other “draw” or “load” attached to either the sign circuit or neutral. What this means is that all wiring must be in accordance with NEC and UL 48 which requires a dedicated circuit without shared neutrals. Lack of a clean ground & neutral or fluctuating voltage may cause nuisance tripping

Examples of Wiring
Wiring a multiple lamp sign with a border.

GOOD

POSSIBLE TRIPPING

More Examples of Wiring


GOOD Short “homerun” leads Balanced load	ACCEPTABLE Long “homerun” leads Balanced load	BAD Unbalanced power unit lead Unbalanced capacitive load Possible GFI tripping

Architectural or Cove Lighting can present problems with current loss and ground fault tripping if long or unbalanced homeruns are used.

BAD
ACCEPTABLE May be dim
GOOD - BRIGHT

Note: The long jumper wires in the above installation must be kept away from all surfaces. If this is not done one of two problems could occur. The jumper could cause tripping by allowing one tube to start before the other by means of its capacity to ground. This long jumper will result in a GFI trip.

Odd stroke channel letters can present wiring problems. It will not be always possible to minimize the GTO cable length from the power unit. An example of a single stroke “V” is shown below with different methods of wiring. For best performance, the leads must be supported away from the “can”.


ACCEPTABLE Balanced lead lengths Balanced capacitive load	GOOD Short lead lengths Balanced capacitive load	BAD Unbalanced lead lengths Unbalanced capacitive load Possible GFI tripping

Note:
1. You will probably decrease the driving distance due to the proximity of metal and wiring. In extreme cases, driving distance can be decreased by more than 20%.

2. You may increase the possibility of false tripping due to unbalanced capacitance coupling to the various metal parts.

3. Always support the GTO in the receiving area from the metal with standoffs, etc.

Capacitance Coupling and Distance
NOTE: Distance is the Best Way to reduce Capacitance Coupling and loss.

In the above illustration GTO Cable is shown in three different locations
in an aluminum “can”.

A. The GTO is on the bottom of the “can” in a corner. This situation causes maximum current loss. A loss of 1 mA per foot of GTO or more can occur depending on voltage and application.

B. Current loss has been reduced by 70% by moving GTO cable 0.5 of an inch from the corner.

C. Current loss from “A” has been reduced by 91% by moving the GTO cable 1.25 inches away from the corner and surfaces of the “can”.

The Effect of Temperature on the Power Supply
Increasing temperature in Electronic Neon Power Supplies and Electromechanical transformers will reduce life. An increase in temperature of 10°C (18°C) will result in a reduction of life expectancy of about 50%. To ensure long life, any power supply mounted inside an enclosure must be adequately ventilated. Ventex VT series indoor power supplies have an operating temperature rating of 32° to 104°F(0° to 40°C). Outdoor CL models have a rating of–30° to 122°F (-34° to 50°C.) If the operating temperature cannot be maintained within these limits, then de-rate the driving distances as in the chart below.

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How to reduce installation problems and improve reliability of UL 2161 transformers