Faulty power line carriers of the high voltage direct current (HVDC) scheme between Apollo converter station outside Pretoria and Songo Converter Station in Mozambique could lead to a large loss of power. For accurate maintenance and fault finding of the power line carriers Eskom's maintenance technicians in the Telecommunication Department use a PSM 138 selective level measuring set (50 Hz to 18 MHz), supplied by Wavetek Wandel Goltermann (WWG).
The power line carriers are important components of the HVDC scheme. Without them the scheme cannot operate, which ultimately would lead to large loss of power. Therefore, it is important to use reliable and accurate instruments in order to maintain the carriers.
WWG Product Specialist Rui Godinho says Eskom has chosen the PSM 138 for various reasons. "Eskom knows WWG products have a proven track record of accuracy and robustness. The company used the PS-3 signal generator and the SPM-3 selective level meter until recently but decided to buy the PSM 138 for its outstanding features. It is easier to tune the PSM 138 to selective frequencies using either the keypad or rotating knob as opposed to the older instruments analog type frequency display. The PSM 138 has a built-in sweep generator."
The built-in generator is coupled to the receiver frequency and has a wide output level range. Application-oriented menus, high measurement speeds, graphic display of the results and practical hard copy features provide the support needed when making measurements. These instruments are equally suitable for use in the laboratory or production environment as well as for mobile or on-site field operation, thanks to their powerful range of features, very compact design and battery power supply.
Godinho adds that the instrument is compact and that the generator and level meter is built into one unit. He says the PSM 138 can be optimised for low noise or low distortion operation to match the measurement task, making it suitable for spectrum and network analysis.
"Single or continuous sweep, maximum value memory, marker copy function and marker evaluations are other practical operating features. Measurement of impedance, return loss or common mode suppression versus frequency is particularly quick and easy to make using external bridges."
Godinho affirms that the user-friendly PSM 138 has increased the department's productivity.
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