Application notes

<General Considerations>

1. The sensor uses polar electronic components. When the

polarity of the power supply is mistaken, the sensor is damaged.

2. Static electricity or excessive voltage can increase an offset

voltage in the Hall element, and cause offset voltage to change.

Please exercise care in handling and application.

3. In order to prevent the influence of noise, the use of twisted

cable or shielded cable for the output line is recommended

4. If using this device within a magnetic field generated by other

devices, the specified accuracy may not be obtainable.

5. Our products（several models are excluded ）are adjusted

with the trimming method by the measurement condition

（Load resistance, Power supply voltage）of specification

sheets. Therefore, characteristics（Offset, Output, etc.）and its

deviation may be changed in different circuit conditions from

the measurement condition. All change characteristic items are

not indicated on specification sheets.

6. The performance of current sensors with through-hole（aperture）

is dependent on the position of the primary conductor. Tamura

specifications are based on a primary conductor completely

filling the through-hole（aperture）area.

7. The current sensor rated current in DC Amps.

8. Please use mating connector with equivalent terminal plating

material to insure proper operation and avoid possibility of

‘galvanic corrosion’.

9. Please do not store in high-temperature and high-humidity

storage environment. Please use it after confirming soldering

when it is kept for six months or more.（product soldered with

substrate）

10. We recommend performing a zero offset adjustment by measuring

the offset voltage at startup. In continuously operation for a few

months, or at change of ambient temperature or humidity is large,

we recommend regularly performing a zero offset adjustment at

being idling（it is clear that the current is not apply）.

11. The current sensor doesn't have built-in protection circuit

(devices and fuses, etc.). As a failure mode of the sensor,

there is a short circuit and open state. In the case of a short-

circuit state, the abnor-mal temperature rise of the internal

parts is assumed, and there is a possibility to smoke and to

ignite. If it is used in safety critical circuit blocks, please take

appropriate measures by protection devices, protection circuits,

etc. For closed loop –type sensors and flux gate (closed loop

type) sensors, the consumption current of the secondary power

supply varies in proportion to the measurement current.

<Open loop>

1. High frequency primary current may result in excessive heating

in iron magnetic core and cause damage to internal circuitry;

for high frequency applications select current sensor with ferrite

core material.

2. If the measured current exceeds the rated current, magnetic

core saturation will occur and the output voltage signal will not

be linearly proportional to the measured current.

<Closed Loop>

1. For closed loop current sensors please insure the power supply

voltage is balanced, symmetrical, and, applied simultaneously

to avoid potential increase in DC offset error.

2. Maximum rated current measurement duration is timedependent.

Maximum rated current applied in excess of the time limit can

result in damage to internal electronic circuitry; please consult

Tamura for assistance.

3. When using a measurement resistor to convert current output

to voltage output select a resistor with stable temperature

characteristic to insure accuracy of the output voltage.

4. Compensation current supplied to the secondary winding varies

in proportion to the measured current based on the conversion

ratio.（If/KN; KN ＝ secondary turns）Please insure the PSU

has required current capacity to supply compensation current

to the secondary winding.

<Flux-Gate>

1. Compensation current supplied to the secondary winding varies

in proportion to the measured current. Please insure the PSU

has required current capacity to supply compensation current

to the secondary winding.

2. There is 450kHz ripple voltage present on the output and

reference output voltage signals . An external capacitor maybe

added if necessary.

CURRENT SENSORS

Appli note 1/1

3 1709

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