YSI IQ SensorNet 2020 XT Terminal - Manual (Page 162)

What to do if ... System 2020 XT USB
7 - 2 ba76019e01 12/2012
7.2.2 Measuring the voltage
If an MIQ module shows an error condition (both LEDs off), this can be
due to the following causes:
 The voltage supply has been interrupted
 The available voltage is not sufficient; the voltage is below the
warning range.
These two cases can be differentiated with a voltmeter.
Measuring points of
MIQ modules
The supply voltage is tapped at the following points (Fig. 7-1 on page
7-3):
 Outside on the free contacts on the front of the SENSORNET
module
 Inside on the SENSORNET connections of the terminal strip (see
section 7.2.2 M EASURING THE VOLTAGE ).
Measuring points for
IQ sensors
The supply voltage is measured on the MIQ module to which the
IQ sensor is connected via the SACIQ sensor connection cable.
Systematic voltage
measurement
Dock all mobile components (terminals) onto the modules with the
greatest distance to the next power supply module. Begin measuring
the voltage at the MIQ modules that are directly connected with an
MIQ power supply module. Continue to measure the voltage
systematically to the end of each cable section, i. e. along the voltage
drop. Thus, in combination with the log book entries, you can narrow
down the error location.
Warning
If the MIQ/PS power supply module is opened during operation,
there is a danger to life due to possible hazard of electric shock.
There is also a danger to life from voltages that may present a
hazard of electric shock on the relay contacts of open MIQ output
modules (e.g. MIQ/CR3). Note the following points in the case of
voltage measurement during operation:
 The voltage measurement may not be performed on the open
MIQ/PS power supply module. The MIQ/PS may only be opened
when the line voltage is switched off.
 The voltage measurement at an open MIQ output module with
relays may only be performed if all external voltages have been
previously switched off.
 Secure all voltages that have been switched off against being
switched on again for the duration of the work.