HiTeC & Yokogawa - emitec-industrial.ch
HiTeC & Yokogawa - emitec-industrial.ch
HiTeC & Yokogawa - emitec-industrial.ch
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ux TM CurrenT SenSorS<br />
extreme high accuracy: 0,1% of a 1 GW transformer<br />
ct Current transmission. Shown here are the three-phase<br />
tion in Eemshaven (NL) with a total power transmission<br />
accuracy<br />
The accuracy of the Hitec Zero-flux TM<br />
CT sensors mat<strong>ch</strong>es perfectly with<br />
the high accuracy of the power<br />
meters from <strong>Yokogawa</strong>. The typical<br />
accuracy of a Zero-flux TM CT with a<br />
closed type sensor head is 0.01%<br />
of the rated current (50Hz). Closed<br />
AC/DC-type sensors equipped with<br />
Hall-elements do have an uncertainty<br />
of approximately 0.1% of the rated<br />
current.<br />
sPlit-core<br />
A disadvantage in using closed type<br />
current sensors is that the primary<br />
conductors temporarily have to be<br />
disconnected from the load. The<br />
load has to be swit<strong>ch</strong>ed off, eyelets<br />
of the cable connection need to<br />
be replaced if they don’t fit through<br />
the sensor hole etc. This is not<br />
always allowed and at least timeconsuming,<br />
inconvenient and costly.<br />
Often it requires the assistance of an<br />
installation engineer<br />
Therefore Hitec developed the<br />
SC1000 high precision split-core<br />
Zero-flux TM CT, with an overall<br />
accuracy of 0.1% of the rated current<br />
(for DC and AC), where<br />
as traditional clamp type<br />
accuracy normally starts<br />
with a 1% uncertainty.<br />
The SC1000 reduces the<br />
measurement uncertainty<br />
on a 4 MW motor/<br />
generator from 40 kW to<br />
4kW.<br />
multi-Phase anD easy<br />
connection<br />
The Hitec current sensors can be<br />
delivered as a single unit to measure<br />
single-phase current or as a multiphase<br />
system with 3 or 4 Zero-flux TM<br />
CT’s together with a junction unit,<br />
powering all Zero-flux TM CT’s. The<br />
junction unit interconnects the current<br />
sensors and directs all measuring<br />
signals to one output connector to<br />
whi<strong>ch</strong> the <strong>Yokogawa</strong> power meter is<br />
connected.<br />
In case of multiple primary cables per<br />
phase (power generators, distribution<br />
transformers etc.) it is even possible to<br />
parallel the Zero-flux TM current sensors<br />
to measure higher currents.<br />
The standard cable length between<br />
the sensor head and the junction unit<br />
is 3 meter. Up to 50 meter of cable<br />
length is possible on request, more<br />
than 50 meter, depends on the local<br />
noise environment.<br />
The same flexibility applies for the<br />
cable length between the junction<br />
unit and power meter.<br />
measurinG ac-current incluDinG Dc-current; the Zero-flux tm current transformer<br />
■ Measures AC + DC currents at<br />
the same time<br />
■ Isolated from the primary circuits<br />
■ Current output or voltage output<br />
■ Wide bandwidth<br />
■ Also a clamp type is available<br />
■ Can be swit<strong>ch</strong>ed on with primary<br />
current already present<br />
■ Long cables possible for remote<br />
operation<br />
Electrical motors easily draw 300 A or more.<br />
■ Saturation detection circuit with<br />
automatic reset after over current<br />
■ Very high stability and accuracy<br />
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