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17.03.21 en / 371A
The device is supplied with DC auxiliary voltage via terminals A1(+) / A2.
Switching on the auxiliary voltage (Power-On) is followed by an internal
self-test for 10 s (see „Device test functions“). The test process is visible
with the status LED. After this, measurement of the insulation resistance
in the measuring circuits begins and the status LED changes into green.
Measuring circuit
(Insulation measurement between terminals L1(+) / L2(-) on the
coupling device and PE1/PE2 on the insulation monitor)
The insulation monitor RN 5897/240 can only be used with a coupling
device. Max. mains voltage and connection diagrams have to be observed!
To connect the insulation Monitor RN5897/240 to a coupling device the
terminals with identical designations are connected (VSG1, VSG2, L(+),
L(-)) .The votage system to be monitored is connected to L1(+) und L2(-)
of the coupling device.
A broken wire detection that can be disabled provides a fault signal if
both terminals L1(+) and L2(-) are not linked by the connected network.
Broken wire between coupling device and insulation monitor cannot be
directly detected but the the measured value of the insulation resistance
when one or more connections are interrupted, is much lower then the real
insulation value which will cause a tripping of the alarm relays.
The type of the voltage system or the connection method (AC, DC, 3NAC)
has to be correctly adjusted on the rotational switch "UN"
Also the terminals PE1 and PE2 have to be connected with 2 separate
wires to the protective earth. An interruption of a wire also causes a fault
signal (see section ”Behavior on faulty connection”). The monitoring of
the PE connection cannot be de-activated.
To measure the insulation resistance an active measuring voltage with
changing polarity is connected between L1(+) and L2(-) and PE1/PE2.
The duration of the positive and negative measuring phase depends on
the actual leakage capacity of the monitored system and in DC systems
also on the level and duration of possible voltage variations. This allows
a correct and fast measurement in different network conditions.
At the end of a measuring cycle the actual insulation resistance is produced
and indicated. The relay for alarm K1 switch when dropping under the
adjusted response value. In addition the status LED lights up red on alarm.
Manual reset of fault message
With the 2-section rotational switch "UN", manual or auto reset of the alarm
can be selected. If manual reset is activated the insulation fault signal of
the measuring circuit is stored when dropping under the adjusted response
value also if the insulation resistance goes back to healthy state. Pressing
the „Reset“ button on the front side for 2 s, the alarm signal is reset if the
actual insulation resistance is in healthy state.
Indicator relay for insulation fault and device failure
The function of the relays K1 (contacts 11-12-14 for alarm) and K2
(contacts 21-22-24) can be altered between energised on trip (relay n.o.)
or de-energized on trip (relay n.c.). When energised on trip the relays
energize when the value drops below the setting or at decive failure, when
de-energised on trip, the relays de-energize when the value drops below
the setting or at device failure.
Semiconductor output to indicate the insulation resistance
On terminals Y1(+)/Y2 a galvanically separated semiconductor output is
available as PWM (Pulse width modulated) signal that shows the actual
insulation resistance. It is an opto-coupler output with open collector.
This means that an external circuit is required (ext. supply voltage and
pull up/down resistor).
Disable the measuring function
Using the external control input X1/X2 the measuring function of the
RN 5897/240 can be disabled. This could be used when several isolated
voltage systems with individual insulation monitors need to be coupled.
The measuring voltage is set to -90V (negative measuring phase) and
the evaluation of the measurement is stopped. The status of the output
relays is frozen and not changed any more. If the measurement is disabled
the status LED flashes continuously orange. Please be aware, only the
evaluation of the measurement is stopped and the measuring pulse is
interrupted! A high resistive disconnection to PE does not take place
(see internal resistance).
Broken wire detection
As described in section "Measuring circut", the measuring circuits L(1+)/
L2(-) and the protective conductors PE1/PE2 are constantly monitored for
wire breaks – not only at Power-On or a manual or occasional automatic
test. The response time of PE1/PE2 monitoring is only a few seconds.
The response time of monitoring of L1(+)/L2(-) can be up to approx.
2 min. Broken wire detection between L1(+) and L2(-) is performed via
coupled alternating voltage. This alternating voltage is short-circuited if
the terminals are connected to the connected mains at low-resistance.
The device detects that the mains to be monitored is properly connected.
Since this broken wire detection is carried out with alternating voltage, large
capacitances should be avoided between L1(+) and L2(-), since the
capacitive reactance of these capacitances also short-circuits this
alternating voltage. The device would no longer detect a connection fault
on L1(+)/L2(-).
Especially parallel lines should be prevented over larger distances.
If larger capacitances between L1(+)/L2(-) cannot be avoided or if the coupled
alternating voltage interferes with the system, the broken wire detection can
be de-activated on the 2-section rotational switch "Rel." It can be altered
between continuously disabled (Broken Wire Detect OFF), or continuously
enabled (Broken Wire Detect ON) for 10 seconds every 2 minutes. If the
broken wire detection on L1(+)/L2(-) is de-activated no AC voltage is injected.
The broken wire detection on PE1/PE2 cannot be de-activated.
Device test functions
Principally, 2 different test functions are implemented: The "self-test" and
the "expanded test":
The self-test of the device is performed automatically after Power-On and
every full operating hours. It can also be triggered manually at any time by
pressing the "Test" button at the device front for 2 s.
With the self-test, contrary to the expanded test, the status of the Indicator
relays is not affected; the sequence is as follows:
The self test is indicated by the status LED with flash code 1 in orange
colour. First the negative measuring pules is activated for about 4 s and the
internal measuring circuit is checked on failures. then the positive measuring
pulse is activated for about 4 s and more internal tests are performed. If no
failures are detected, the normal measurement continuous. The extended
test is started, when during or at the end of above procedure the button
"Test" is pressed again for 2 s.
The procedure is the same as above (2 measuring phases with 4 sec each)
but in addition the output relays K1 and K2 go into alarm state and the PWM
on the semiconductor output drops to the lowest value. The Status LED
shows flash code 2 in orange colour. The test phases will be continuously
repeated. pressing the button "Test" for 2 s will end the extended test
immediately. the device starts the again the insulation measurement.
Behaviour with internal device faults
If internal device faults were detected during the test function, the status LED
flashes permanently red. The indicator relay K2 switch to the alarm state.
Behavior on faulty connection
When detecting broken wire on terminals L1(+)/L2(-), the measurement is
disabled. The reaction time could be up to 2 min. The monitoring relay K2
goes in alarm state, the status LED shows flash code 1 in red colour. After
removing the interruption the fault is automatically reset (max. reaction time
up to 2 min) and the measurement of the insulation resistance is continued.
Stored alarm values remain stored. An interruption of the protective earth
connections PE1/PE2 causes the same reaction as interrupting the
measuring circuit, only the status LED shows flash code 2 in red colour.
Behaviour at parameter failures
With wrong settings on the rotary switches the device goes to failure mode.
The indicator relay K2 changes to alarm state and the status LED shows
the red flash code 3.
External control input
To terminals X1/X2 an external combined Test-/Reset button can be
connected. If the terminals X1/X2 are bridged for approx. > 1,5 s and <
10 s the test mode is started. This has the same function as pressing the
internal test button. When bridging X1/X2 for < 1,5 s, a stored alarm will
be reset. This has the same function as pressing the internal reset button.
If X1/X2 is activated for > 10 s, the measuring function is stopped.
The measuring function remains suspended for the duration of the control
of X1/X2.
Function
Function
