M-140 Multifunction Calibrator
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Operation manual v46
Connection of a multimeter to be calibrated (voltage range) to the terminals of 140-01 cable adapter
Current ranges
All DC and AC current ranges are connected to calibrator’s +I/-I terminals.
If current is drawn from calibrator’s +I and –I output terminals, +I and –I output terminals located at
140-41 cable adapter must not be connected simultaneously!
When using the current output under heavy load (10 to 20 A), the runtime is limited to 0 to 60 s. The runtime
depends on the set current and it is controlled by the microprocessor. The user cannot extend the runtime; if longer
runtime is required, the output terminals must be unloaded, some time must elapse (for example1 min.) and the
load can then be connected again.
When feeding 2 to 20 A current to the output terminals, the output voltage must not exceed approx. 1.5 Vef. If the
current induces higher voltage on the load, the calibrator disconnects the output terminals and displays an error
message.
When ammeters are being calibrated using currents over 1 A, it is important to connect the terminals properly,
paying attention both to the calibrator’s output terminals and the instrument’s input terminals. Excessive contact
resistance can heat up the terminals and cause calibration errors. Excessive and unstable contact resistance has
non-linear characteristic and can distort the output AC current.
It is not recommended to connect non-standard load to the current output. The calibrator is designed to be used for
calibration of ammeters. Output terminals should be loaded with low and real impedance. Although the output is
fitted with fast electronic and microprocessor protection, high capacitance or inductance can lead to oscillations
of output amplifiers and result in damage.
The instrument to be calibrated can be connected either directly to the front panel terminals, or to Opt.140-01 cable
adapter. If L terminal of the instrument to be calibrated is not grounded, then calibrator’s -U (-I) terminal should
be grounded (GND U ON, GND I ON, see „Setup menu“ chapter).