MEASURING DISTANCE UP TO 320 FT (100 m).
SELF-TESTING OF MONITORING UNIT.
MEASURING CABLE AND SUM CURRENT TRANSFORMER
APPLICATIONS OF SUPERINTEND VRE-10
Supervision of a grounded (3-phases+N+G / 3-phases+G / 1-phase+N+G) high resistance grounded distribution power system
In a grounded distribution system the return current flows through the neutral conductor (N) back to the main ground bus. The current in the grounding (G) conductor is theoretically zero. However, in actual practice there is a small current in the G conductor – the so called inherent leakage current. It is caused by different devices, filters, and big fluorescent lamp groups connected to the electrical system. This leakage current increases if faults occur in the distribution system from insulation damage in the devices connected to the distribution system or from wiring errors in the electrical system itself. These faults may appear as faults or short circuits between the ground conductor and the power supply. It is important to detect an emerging fault and remove it quickly in order to guarantee the proper operation of the grounded electrical system. A continuous fault situation may be hazardous for the user, for the equipment connected to the electrical system as well as to the system itself (overheating, arching faults and fire risk).
Detection of wiring error
Wiring error may spoil the advantages of a grounded electrical system from being achieved and cause hazards for the user.
With the help of a supervision unit the wiring errors may be detected immediately. Possible wiring errors are:
- N and GND conductors are connected together,
not only through the main ground bus.
- N and GND conductors have been swapped somewhere in the electrical system
- A load has been connected between a phase conductor and the ground
- A device is grounded through its installation parts
- Neutral to neutral wiring errors (if the measurement is close to the load)
ON-LINE detection of insulation faults
The most usual reason for a fire risk is the damage in the cable insulation. This may occur due to overloading, excessive moisture, insulation deterioration, mechanical stress, etc. The supervision equipment detects an incipient insulation damage as the fault current value rises. The Superintend system detects an arcing fault before a fuse or a circuit breaker operates.
Supervision of the integrity of a distribution network
Leakage and stray currents cause potential differences and disturbance voltages in computer and building management networks. These power disturbances are particularly harmful in data lines. If a partial or complete short circuit occurs between the N and G conductors, the electrical system operates as a four-conductor system. In this case the benefits of a five-conductor system are lost. Only by continuous supervision of a grounded electrical system, can the system be kept “clean”.
Measurement of small currents
With this Supervision Unit it is possible to measure small currents in the range of 5 mA to 10 A.
CONTINUOUS MONITORING OF ELECTRICAL INSULATION
Over time leakage current increases because the insulation begins to degrade. By continuous monitoring of leakage current, weakened insulation can be identified before the circuit breaker trips and production is shut down.
