T&R KV50-20D mk2, Operating And Maintenance Manual

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1.1.5.1 Variable overload
The variable overload protection system senses current changes in the high voltage circuit. The
trip level is adjusted by means of a selector switch on the front panel of the unit. The switch
allows the level to be adjusted from 2-22mA in 2mA steps.
The circuit will activate when the load current exceeds that set by the trip level selector switch.
The circuit will respond more slowly to slowly changing levels of load current.
WARNING
The variable overload trip circuit does not limit the output current on short
circuit.
1.1.6 Metering
The equipment is fitted with a two-range kV meter that indicates the output voltage. It is also
fitted with a mA meter that meters the output current in the earthy end of the HV side of the
output transformer.
Range
KV meter mA meter
FSD Resolution FSD Resolution
Range 1 19.99kV 0.01kV 19.99mA 0.01mA
Range 2 50.0kV 0.1kV - -
The output voltage is metered from the primary of the HV transformer, and as a result the
accuracy of the kV meter is dependent on the output current. The values for accuracy at different
load currents are given below.
Load
current
kV
accuracy
<2mA 2-8mA >8mA
20.00kV range ±2% rdg ±5d ±4% rdg ±5d ±5% rdg ±5d
50.0kV range ±2% rdg ±3d ±4% rdg ±3d ±5% rdg ±3d