OVERVIEW

Developed after coronial inquest into electrical deaths in premises, the Dewar model M1110A Neutral and Supply Tester was designed in conjunction with the Victorian power authorities to ensure the incoming Active and Neutral power connections to customer’s premises are correctly identified and safe to use before a power connection is made.

The M1110A is a compact hand held unit housed in a lightweight heavy-duty case.  The M1110A is a self powered passive device.  Power is taken directly from the user’s connections to the IEC connector. The front panel has 5 LED indicators.  An audible alarm is fitted internally as a secondary indicator to indicate a failure. These indicators will show the safety status of the connection

OPERATION

Electrical connection is made to the M1110A via an inbuilt IEC320 connector.

The testing cycle is instigated automatically when the appropriate wiring connection is made to the M1110A.  The M1110A has no user selections to instigate testing. The M1110A is designed to automatically start checking as soon as power is applied.  If the neutral to active impedance is out of tolerance the unit will indicate a fail and further testing will cease to occur, indicating the failure mode.

TESTS PERFORMED

Self Check

1. Applied voltage greater than 150 VAC and no internal self test failure is a pass.

2. Applied voltage less than 150 VAC or an internal self test failure is a fail.

A failure at “Self Check” will be indicated by three flashing red LED’s plus an audible alarm. Further testing cannot proceed.  After a successful internal self check, live testing of the power lines will automatically proceed.

Live Test Performed

1. Active to Neutral voltage less than 195VAC.     Indicates a fail.

2. Active to Neutral voltage greater than 277VAC.    Indicates a fail.

3. Neutral to Earth voltage greater than 5.25VAC.    Indicates a fail.

4. Earth impedance greater than 10K ohm.     Indicates a fail.

5. Neutral to Earth voltage is greater than Active to Earth voltage. Indicates a fail.

6. Active to Neutral impedance greater than 1 ohm, +/-5%   Indicates a fail

A failure in 1, 2,5 and 6 of the above live tests will result in one red LED being illuminated plus an audible alarm.

A failure in 3 and 4 of the above live tests will result in two red LED’s flashing plus an audible alarm.

Failure of any tests will be indicated by one of any red LED indicator being illuminated

Pass is indicated by continuous illumination of “ Ready/Pass” green LED.

Safety status of the connection.

When the M1110A to connected to power, the units performs internal self checks, checks the voltages connected to the unit and the active to neutral impedance is measured to ensure less than 1.0 ohm  impedance. (accuracy +/-5%)

Greater than one ohm indicates a failure.

Failure is indicated by a continuously illuminated red LED and an audible alarm.

Safe to proceed is indicated by the continuous illumination of both the “power” LED indicator and the green ‘Safe to Proceed ” LED indicator and no audible alarm.

Failure of any tests will be indicated by one of any red LED indicator being illuminated