Surge voltages are forever causing considerably high sums of damage to industrial plants, offices, surgeries, private households and even the technical equipment of leisure facilities. The Bad Pyrmont Golf Club is one of these, and has in the past often been struck by surge voltages. A stop is being put to this with the installation of a surge voltage protection concept for the electronically controlled sprinkler system.

A major requirement of the quality of a golf course is the state of its green. The golfer can only aim his puts accurately on well-tended and closely-grown grass. The electronically controlled sprinkler system sees that the green is tended even on dry days. The system's controller is programmed correspondingly and the green is watered automatically and discreetly in the evenings after the last golfer has left the course.

Such a system has been installed on the course of the Bad Pyrmont Golf Club e.V. on the border between East Westphalia-Lippe and Lower Saxony. The idyllic yet exposed location of the golf course does not immediately bring to mind the dangers of surge voltages. But Josef Hiller, a long-standing member of the golf club committee and proprietor of Elektro-Pytron, Lügde, can tell a tale of the regular damage to the sprinkler station: "The control system of the watering unit used to be out of operation after almost every storm. The system then had to be repaired at short notice so that the grass was not burnt if dry hot days followed. Since we installed the Trabtech surge voltage protection equipment, there has been no further damage due to surge voltages".

Elektro-Pytron is an electrics company with a staff of 35. Fritz Hundertmark, the director explains: "It is imperative to keep up on the latest topics in electrotechnology. We have therefore been sending our staff to reputable manufacturers or centers for many years for training so that we are in a position to give our customers expert advice and to install and service the systems professionally. Advice on surge voltage protection is therefore also an integral part of the service to a customer."

On the subject of technology

The golf club has its own well that is used both for water for the tank of the sprinkler system, and for fresh water to supply the club house. Three pumps take care of transporting the water from the well from a depth of 122 m to the two water tanks. Parallel to the main pump, one of the two downstream pumps is also on. Priority is either given to fresh water for the club house, or the tank of the sprinkler sytem is filled.

The level in the water tank of the sprinkler sytem is measured with three dip-coated electrodes. The measured data are evaluated electronically and the relevant downstream pump is switched on until the desired level is reached. There is a further pump with a power of 12 kW downstream to ensure the necessary water pressure in the watering system. A water pipe runs from this pump to each of the 20 greens on the golf course – 18 tournament and two driving ranges. In the greens, the water pipe ends in an electrically operated solenoid valve and is divided in a star-shaped arrangement between three to four sprinkler segments. To guarantee a constant water pressure to the green for watering, the areas to be watered are switched on one after the other so that only one solenoid valve is ever open at a time.

The protective concept

Following the principle of a protective circuit, it was necessary to include all the lines leading to the watering system in the protective concept. This includes the low voltage supply, pumps, water level indicators, solenoid valves and the outside lighting. Since all the lines are laid underground in the open, danger from direct lightning strikes is to be expected. The experience of damage in the past has shown that the water tank was often hit directly by lightning. In such cases, the ground potential increases to several 100 kV. This results in direct interference in the equipotential bonding system and surges in the active parts of the electric system. Damage is then the unavoidable consequence.

The low voltage supply was connected from L1, L2, L3 and N to earth downstream of the main fusing using four VALVETRAB surge voltage arresters. The same combination of arresters was used at the connection of the three-phase pump shed infeed line, since surge voltages can also cause interference along this line. The surge voltage arrester, VALVETRAB has a high-capacity varistor as protective element. If the protective element becomes overloaded, the integrated temperature control is triggered and signalizes the fault via a display.

The lines to the field decoders to protect the pumps and pipeline pressure monitoring devices against running dry are protected with MCR Plugtrab UFBK 2-PE-48AC. This protective device is designed with a three-stage circuit, consisting of high-capacity gas-filled surge voltage arresters, varistors and fast-reacting suppressor diodes. Reliable protection for floating signal interfaces is thus achieved.

The MCR Plugtrab UFBK 2-PE/L is used for the protection of the three-wire measurement from the water level indicator and the pressure transmitter. The three-stage protective circuit is designed for three signal wires. A protective path is connected to the metal PE foot of the protective device. The arresters were therefore installed with insulation between the mounting plate.

The protective devices from the MCR Plugtrab product family can control surge voltages up to 10,000 A and at the same time limit them to a level that lies below double the nominal voltage of the device to be protected.

The feed lines for requesting water and for the outside lighting for the pump shed have been wired with Mains-Plugtrab UAK 2-PE/S 230. This arrester has a protective circuit designed for a 230 V equipment connection. Temperature monitoring of the components, coupled with optical signalling, ensures clear fault warnings in the case of an overload caused by surge voltages.

The success of this protective measure is indisputable, since there has been no damage due to surge voltages since the protective equipment was installed.