Besantek BST-GFL31, Руководство пользователя

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BST-GFL31 User Manual
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2.6.2 Gross searching
Physically divide the DC system into several sections. For example, in power substation, there are
different cabinets in the same DC system. These cabinets can be chargers, switchgears, control panels
and so on which we consider as different bigger loads. Wiring structure could be complicated and most
of the time different wires are tied together.
In this case, you do not need to check wire by wire. You could connect the current clamp around input
and output terminal of each cabinet (load) to see the current strength, phase angle and direction
compared with reference point. Most of the time, input and output of this cabinet (load) are bound
together; you could just use one clamp. If they are far away, use two clamps with arrow mark pointing to
the load.
This way of gross searching will be time saving and no need to take out all the wires that have been tied
together inside the cabinets. But when using this way, make sure that you are familiar with the wiring
structure of the DC system, which will help you find out the fault much faster.
2.6.3 Use more than one signal receiver
To save time, you could have more personnel holding more signal receiver checking simultaneously to
narrow down the scope of signal searching. All BST-GFL31 signal receivers (of same frequency) could
be used at the same time independently for ground fault location. They can have separate setting for
reference point which will not affect each other.
2.7 Signal Changes in Earth Fault Circuit
We have explained in detail on how to pinpoint the ground fault in the previous context. Here is further
illustration for signal changes in the circuit.
Supposed that there is ground fault on positive busbar as exemplified in Fig 2.7, red testing lead is
connected with positive busbar and black lead with ground. Branch c has ground fault.
Signal generator will inject a voltage signal in the circuit. Due to the existence of distributed capacitance
and grounding resistance, there will be leakage current. Current signal and phase changes will be like (b)
and (c) in Fig 2.7. There will be sudden changes before and after the point of fault. Phase angle will be
lowest at the point with ground fault.
In the diagram, branch c has a grounding resistance R. I
R
is the resistive current. C1 and C2 are
distributed capacitance. I
c1
and I
c2
are capacitive current.
Note:

In new reference point setting, please still use only ONE clamp with arrow mark
point towards the fault, same as the first reference setting. Clamp it around red
line if fault is on positive busbar, otherwise, clamp around black line.

You are strongly suggested to make the record on where you set the second
reference point and with what current strength. You may have to come back and
trace the second highest signal (can be another fault) in the same Level.