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imc C-SERIES - Manual, Version 4 R 3 - 2018-10-19

17Potential difference with synchronized devices

2.10 Potential difference with synchronized devices

When using multiple devices connected via the SYNC plug for synchronization purposes, ensure that all

devices are at the same voltage level. Any potential differences among devices may have to be evened

out using an additional line having adequate cross section.

Note

If the synchronized devices are at different voltage levels, they should be compensated by means of a

lead having the appropriate cross-section. If the SYNC plug at your device is equipped with a yellow ring

it is already isolated and it is protected against potential differences (concerning devices as of

summer 2012).

Alternatively it is possible to isolate the devices by using the module ISOSYNC, see also chapter

Synchronization in the imc STUDIO / imc DEVICES manual.

2.11 Fuses (polarity-inversion protection)

The device supply input is equipped with maintenance-free polarity-inversion protection. No fuses or

surge protection is provided here. Particularly upon activation of the device, high current peaks are to be

expected. When using the device with a DC-voltage supply and custom-designed supply cable, be sure to

take this into account by providing adequate cable cross-section.

2.12 UPS

Devices with DC supply input are equipped with an uninterruptible power supply (UPS). This allows for a

continuous operation unaffected by temporary short-term outage of the main power supply. This type of

operation is particularly useful for operation in a vehicle, permanently attached to starter lock and main

power switch and thus not requiring manual control. Activation of UPS buffering is indicated by the

power control LED (PWR) changing from green to yellow. With many imc measurement devices, active

UPS buffering is additionally indicated by an acoustic buzzer signal.

The UPS provides backup in case of power outage and monitors its duration. If the power outage is

continuous and if it exceeds the specific device’s "buffer time constant", the device initiates an automatic

shutdown sequence, which equals manual shutdown procedure: Any current active measurement is

automatically stopped, data storage on flash card or internal harddisk is completed by securely closing all

data files, and finally the device is actually switched off. This entire process may take a couple of seconds.

Thus, a typical application of this configuration is in vehicles, where the power supply is coupled to the

ignition. A buffer is thus provided against short-term interruptions. And on the other hand, deep

discharge of the buffer battery is avoided in cases where the measurement system is not deactivated

when the vehicle is turned off.

If the power failure is not continuous but only temporary, the timer that monitors blackout duration is

reset every time the main supply has returned to valid levels. The buffer time constant is a variable

device parameter that can be configured according to system size and battery capacity. It can usually be

written into the device under software control and is preconfigured to reasonable default values upon

delivery (see description in the software manual).

IMC C SERIES User Manual

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