DC Wave Filter and Surge Capacitors (To Transnet Specifications)
Rated at 3,4kVDC, the 10µF , 20µF and 50µF, the ZEZ Silko wave filter capacitors are used for harmonic filtering in 3kVDC traction substations. The capacitors are used with resonant shunts to reduce the magnitude of the 6th, 12th, 18th and 24th harmonics at the busbar of the 3kVDC rectifier traction sub-station. The 3kVDC/4µF ZEZ Silko capacitor is used to protect Transnet Freight Rail electrical equipment against surges caused by lightning. The ZEZ Silko capacitors use All Film technology, the dielectric is polypropylene foil impregnated with non-toxic, non-PCB environmentally friendly and biodegradable synthetic oil. Capacitor discharge is effectively achieved by internal discharge resistors that will discharge the capacitor voltage to 50V within 5 minutes. The capacitor cases and mounting brackets are manufactured from Stainless Steel that is polyurethane coated to ensure prolonged durability. The wave filter capacitors are supplied as temperature category -10/D, and the surge absorber capacitor as temperature category -40/D. The wave filter and surge absorber capacitors comply with the Transnet Technology Management specifications BBB3139 and CEE0115 respectively.
DC Voltage Detectors
Used to test for the presence or absence of supply voltage in direct current substations, switchgear and overhead line installations. The PHE/G series voltage detectors can be used in wet weather conditions for voltages from 1kVDC up 24kVDC. The voltage detectors provide reliable indication, are easy to use and the modular design makes it easy to transport. Voltage present is indicated by a bright red light indication and voltage absence is indicated by a constant bright green light indication.
Portable Earthing Equipment for Railways
Used for the earthing and short-circuiting of electrical installations before work commences. These devices are used in sub-stations, overhead lines, distribution panels and DC traction systems to ensure the safety of electrical personnel if supply voltages are reconnected accidentally. The ratings of these devices are based on short-circuit current and the time duration for protection relays to operate and issue a trip signal to the supply breaker.
Voltage Limiting Sparkgaps for Railways
The voltage limiting devices are used to prevent the occurrence of hazardous voltages between the insulated tracks or track sections of electric railways and the earthed parts of the installation. In the event of atmospheric overvoltages, the lightning resistant SDS voltage limiting device is capable of returning to its initial state after discharging the impulse current. If the specified lightning current load is exceeded, a permanent short-circuit is initiated by high-current resistant welding of the electrodes and the voltage limiting device has to be replaced. The SDS voltage limiting devices consist of a sparkgap unit and the respective connecting kit and can be directly connected to the rail or overhead contact line tower.