DOLD VARIMETER IMD RN 5897/300 Technik der Überwachung - Seite 2

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Function

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 12 sec (see „Device test functions"). The test process is visible

in the status LED. After this, measurement of the insulation resistance

in the measuring circuits begins and the the colour of the status LED

changes to green.

Measuring circuit

(Insulation measurement between terminals L(+) / L(-) and PE1/PE2)

The terminals L(+) and L(-) are connected directly to the voltage system

to be monitored. A broken wire detection creates a fault signal if there is

no low-ohmic connection between both terminals.

The type of network (AC, DC, 3NAC) has to be selected.

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 L(+)/L(-) and PE1/PE2.

At the end of a measuring cycle the actual insulation resistance is produced

and indicated. The relays for alarm K1 and pre-alarm K2 switch when

dropping under the adjusted response values. In addition the LED changes

to orange color on pre-alarm or to red color on alarm.

Manual reset of fault message

The rotary switch "UN" is devided in 2 sections. So additional to the type of

voltage system also manual or autoreset can be selected. (Alarm storing:

manual reset, no alarm storing: auto reset).

If manual reset is activated the insulation fault signals of the measuring

circuit are stored when dropping under the adjusted response values

also if the insulation resistance goes back to healthy state. Pressing the

„Reset" button on the front side for 2 s, the alarm signal are reset if the

actual insulation resistance is in healthy state.

Indicator relay for insulation fault signal

For the indicator relays K1 (contacts 11-12-14, for alarm) and K2 (contacts

21-22-24, for pre-alarm) the function energized on trip or de-energized on

trip can be set via pre-alarm rotational switch "R

resistance drops below the adjusted response value.

Broken wire detection

As described in section "Measuring circut", the measuring circuits L(+)/L(-)

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 monitoring is only a few seconds. Broken wire detection

between L(+) and L(-) 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 L(+) and L(-), since the capacitive

reactance of these capacitances also short-circuits this alternating voltage.

The device would no longer detect a connection fault on L(+)/L(-).

Especially parallel lines should be avoided over larger distances.

If larger capacitances between L(+)/L(-) cannot be avoided or if the coupled

alternating voltage interferes with the system, the broken wire detection

can be de-activated using alarm rotary switch "R

or continuous monitoring (every 2 minutes for 10 sec) are the possible

options. If the broken wire detection on L(+)/L(-) 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 sec.

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 via LED with orange flash code 1. For approx.

5 s to negative test phase. Within these 5 s the internal measuring circuit

is checked for failures. Then the measuring pulse is switched for approx.

5 s to positive test phase and more internal tests take place. If no failures

turned up and had been recognized, the measurement continuous. The

extended test procedure is started when during or at the end of the above

described self-test (12 s) the test button is pressed again for 2 s.

The sequence is similar to the self-test (2 measuring phases of 5 s each)

but in addition the output relays go in alarm stated. The LED shows

orange flash code 2. The test phases of the extended test will be repeated

continuously. The extended test can be finished after the first complete

sequence (approx. 10 sec) by pressing the "reset" button for 2 seconds.

The device starts the insulation monitoring again.

Measuring voltage

Relay state K1 and K2

Test signal: Button Test > 2 s or X1/X2 < 3 s

Reset signal: Button Reset > 2 s or X1/X2 > 3 s

To initiate the extended test (Test 2) the test signal must be operated

" when the insulation

within the self test (Test 1) again.

The reset signal has here no function, as the first complete sequence

of extended test (Test 2) is not finished.

". Monitoring deactivated

Self test (Test 1)

Insulation

measurement

Duration: approx. 12s

Positive

Negative

Test signal

Reset signal

Alarm

No Alarm

Self test (Test 1)

Continuous extended

Insulation

Duration: approx. 12s

test (Test 2)

measurement

Duration: approx. 10s

M12462

10.11.23 en / 800A