We receive a lot of questions from our customers. In them the various actions connected to the operation of the mobile test vans and equipment delivered by our company are mentioned.
On this page we shall place on a regular basis the most interesting of them.
1. Electricity Authority of Cyprus.
Question:
In which cases can an electrical operator use the induction method for pinpointing and pre-locating cable damages and in which cases the acoustic method?
Answer:
The induction method is intended for pinpointing cable damages when phase –to- phase faults have taken place. This method is effective when there is a conductive bridge in the place of damage and the resistance of this bridge is not more than 1Ohm.
The essence of the method is the analysis of changes of the AC electromagnetic field which is carried along the cable track. The changes take place if the operator uses a special audio frequency sine-wave voltage generator. The alternating electromagnetic field with the help of an induction sensor, a receiver-amplifier and head phones is transformed into audio oscillations. The operator can pinpoint and pre-locate the cable trace, the depth of the cable and the place of damage by hearing the changes of the audio frequency in his head phones.
The acoustic method is intended for pinpointing of cable damages.
This method is effective if there is a disruption between the cable core and the cable sheath. A conductive bridge is absent. Optimal resistance in the place of damage is 200 Ohm up to 2 Km.
The essence of the method is to produce powerful electrical discharges in the place of damage, which are produced by a special high-voltage generator. The audio effect can be heard from the surface of the ground with the help of audio sensor, audio receiver and head phones.
2. Electrical networks company. Philippine Republic.
Question:
Does the use of a reflectometer which is included in a complete laboratory set have any influence on the efficiency of pinpointing of cable damages?
Answer:
If there is no reflectometer in a complete set of the laboratory it takes much more time for the operator to pinpoint and pre-locate the cable damages. He/she must work along the cable track, sometimes for several kilometers to find the place of damage. If the operator will use a reflectometer to pinpoint the place of damages beforehand, the search zone is limited to only a few meters. The search time is thus shortened.
3. Electrical power station. Shanghai, China.
Question:
What equipment for measuring the parameters of high-voltage transformers can be delivered by VITALDRIVE?
Answer:
For measuring the parameters of power transformers the following equipment are available with a mobile test van:
Built-in adjustable voltage source 0…. 380 V
4-strand cable to connect to the DUT
Connection terminals on the control desk which are connected to the output of a voltage source and strands of measuring cable.
2 multimeters for measuring the turns ratio of 1– and 3- phase transformers.
Digital energy analyzer for voltage, current and resistance measurements. It is used for single-phase transformers in a short – circuit mode.
Digital milliohmeter for resistance to D/C measurement of the winding coils of transformers and electric motors.
4. Companies performing water pipes repairs. Cyprus.
Question:
In which cases is a correlation leak detector used?
Answer:
A correlation leak detector is used for remote locating of water leakages in underground water pipelines at a distance of up to 1 km. Water leakage sensors are placed on the water pipeline in 2 places. Acoustic noise, which is produced on the reason of leakage, is transmitted to a correlation device by radio. A correlation device analyses the signal, identifies both sensors and calculates the distance between one of the sensors and the place of water leakage. A correlation leak detector is used for pre-location of the water leakages. For pinpointing of the water leakages acoustic leak detectors can be used.