Instability Of The Zero Point; Large Noise - KYOWA DPM-900 Series Instruction Manual

7-4 INSTABILITY OF THE ZERO POINT

¨ When preheating is insufficiently
Preheat the DPM-900/950 series approximately 30 to 60 minutes. For details, read "5-3 PREHEATING."
¨ When the insulation of the strain gage or leadwires is low
Repair or replace it.
¨ When the temperature compensation is insufficient
Use the strain gage having the sufficient temperature compensation.
¨ When the fixed resistors incorporated in the bridge box are no good.
Repair or replace them.
Contact KYOWA or our representatives if the trouble still remains after carrying out the proper remedy.

7-5 LARGE NOISE

The cause can be the following.
Inductive Interference
A nearby instrument having a large leakage flux can be the cause of induction noise. A large capacity
motor and an iron-resistance constant-voltage instrument are a few examples. In addition, when the
measuring point is far from the DPM-900/950 series, the induction noise may generate.
Remedies are as follows.
• Place a causative instrument apart from the DPM-900/950 series.
• To connect the strain gage to the amplifier, use a 2-conductor flat cable at least. If possible, use a
2-conductor shielded cable, which is the ideal. In this case, connect the shielding wire to the
ground terminal E of the bridge box.
Interference due to a measuring object's electric potential
This interference occurs when a measuring object has a certain electric potential, AC or DC. In this case,
grounding the DPM-900/950 series does not necessarily bring about a good result, but connection of a
measuring object to the DPM-900/950 series can be the solution in some cases.
In addition, in case of inductive interference or if measuring object has a certain electric potential, it is to
solve the problem by a simple method. Especially, the number of devices that are used in the same
measuring environment is increasing resulting in interfering with each other as noise resources. The
above remedies are just a few examples to solve the noise interference. Fully consider the operating
environment and take an appropriate remedy to obtain the most efficient results.
38