Page 108 - Current & voltage sensors catalog

Calculation guide
Electronic technology voltage sensors VS sensors

2.2 - What are the consequences, if the required signal is only 5 V (VM = 5 V)?
In the same way as for closed loop Hall effect current sensors, if the required measuring voltage is
1SBC146038V0014 signal with the conditions used in the preceding point.
reduced, carefully check that the ±15 V (±5%) supply used in this example is sufficient to obtain a 5 V
i.e. R M = 66.67 Ω
R M = V M / I S
= 5 / 0.075
R M = [(0.8 x V AMIN) / I S] – 55 = [(0.8 x 14.25) / 0.075] – 55 i.e. R M = 97 Ω
VS1000B
We therefore verify that the sensor measures this 1500 V voltage since the measuring
resistance with a ±15 V (±5%) supply is 97: for 66.67: required.
2.3 - What is the maximum measurable voltage by a VS1000B in specific conditions?
An electronic voltage sensor is also sensitive to the thermal aspect.
4 In general, a VS voltage sensor can withstand up to 150% of the nominal primary voltage, but only under
certain conditions.
In all these cases, we recommend that you contact your distributor in order to obtain detailed
information on this subject.
2.4 - What influence does the ambient temperature have on the sensor's performance?
The electronic voltage sensor design means that the maximum operating temperature influences the
sensor's performance, notably the measurement accuracy. However there is no correlation between a
reduction in the ambient temperature and an increase in the voltage to be measured.
2.5 - What influence does the supply voltage have on the sensor performance?
In general, the higher the supply voltage, the higher the measuring voltage. The thermal aspect of the
sensor should be considered.
NB: for calculations with unipolar supply (e.g. 0…+24 V), contact your distributor.
2.6 - What influence does the temperature have on the sensor's life time?
From a general point of view, with whatever product, the more the temperature, the less the life time.
With the VS sensors, the temperature also reduces the life time above 40 °C. The factor of reduction is
however very much depending on the way the VS sensors are used in the application. Please contact
your local supplier for further information.
3 - Sensor primary circuit calculation
Maximum common mode voltage
Can the VS1000B sensor (U PMAX = 1500 V peak) be used to measure a differential voltage
U P = U HT+ - U HT- with U HT+ = 3500 V DC and U HT- = 2600 V DC ?
I I I I
3.1 - U HT+ - U HT- = 3500 - 2600 = 900 V DC < 1500 V peak :
I
I
First condition U HT+ - U HT- < U PMAX is therefore fulfilled.
3.2 - U HT+ + U HT- = 3500 + 2600 = 6100 V DC > 4.2 kV peak :
Second condition U HT+ + U HT- < 4.2 kV peak is not therefore fulfilled.
Conclusion
The VS1000B sensor cannot therefore be used to measure this 900 V DC primary differential voltage
(even though this differential voltage is lower than the nominal primary voltage of the VS1000B sensor).
For this application the VS2000B sensor can be used since:
U HT+ + U HT- = 6100 V DC < 10 kV peak
The condition U HT+ + U HT- < 10 kV peak is therefore fulfilled with the VS2000B.

1SBC140073S0201

106 | ABB