Fire Denyer – Fault Finding


FAULT FINDING IN GENERAL

This page is a work in progress and will be expanded as information becomes available.

To fault find and resolve issues, a good general understanding of the system is required.

Assuming a typical installation, the Fire Denyer system consists of a controller (switch) and battery pack that is usually powered from a nearby mains lighting circuit, a contactor (big relay) located in the switchboard and one or more series connected (daisy-chained) smoke detectors throughout the house.

Basic Operation

If the power is not ON or does not return after an alarm and RESET.

The smoke alarm will trip the controller which cuts off power.  Press HUSH on the controller then press RESET.  If the smoke alarms are clear, this should restore power.

If this does not restore power there may be a problem with a smoke alarm.

  1. Check circuit breakers on the switch-board for one that has tripped.
  2. Is there a GREEN or RED indicator on the controller ?
  3. Is a RED indicator on the controller flashing ?
  4. When you press HUSH the RED indicator should flash.
  5. When you press RESET, the RED indicator should stop flashing and power be restored.
  6. If when you press HUSH then RESET the RED indicator keeps flashing and power is not restored, there may be a problem with a smoke alarm.
  7. If when you press HUSH then RESET the RED indicator stops flashing and turns GREEN but power is not restored, there may be a problem with the Fire Denyer controller or at the switchboard – you will need an electrician or report to your landlord.

If this does not help, you will need to talk to your installer or landlord.

Do not tamper with the controller or wiring unless you have a current electrical qualification – this can be dangerous.

NOTE

  • Mains power is dangerous – don’t attempt this if you are not experienced with high voltages
  • Mains power must be applied while testing
  • The controller can be operated without a battery – but should have a battery connected
  • The fuse on the controller is for the load or contactor circuit
  • The controller supplies approximately 12V DC to the smoke detectors
  • The smoke detectors trigger the controller and are linked to sound alarms in all detectors
  • The smoke detector circuit uses a 4.7K end-of-line resistor

Getting Started

The controller needs a good mains power supply; phase and neutral. No earth is required. If the power supply is unstable or switched elsewhere, you have a problem other than the Fire Denyer installation.

Typical Faults

For All Faults

As you would expect, most faults are related to the smoke alarms and controller.

The smoke alarms must have reliable power and be stable.  The controller must see the EOL (end of line) resistor in the last smoke alarm on the circuit.

  • Has the jumper been removed for the last smoke alarm in the circuit ?
  • Do you see approximately 12V DC on the “+” and “-” terminals of each smoke detector ?  No voltage when hushed – press Reset.
  • Do you see approximately 12V DC between “+12” and the Detector “-” terminals on the back of the controller ?  This voltage should always be present.
  • Using a multi-meter – check for approximately 2.49V across the Detector “I” and “-” terminals on the controller.  This represents a normal closed circuit.
  • Is the wiring tidy and neatly stripped and terminated ?  No stray strands ?
  • DO NOT OVER-TIGHTEN terminals.

Alarm Activates Periodically or Regularly

This suggests that the controller is not seeing a reliable EOL (end of line) resistor in the last smoke alarm on the circuit.

  • Is the smoke circuit wiring tidy and neatly stripped and terminated ?  No stray strands ?
  • Does moving wiring, bumping or moving a smoke alarm or the controller cause it to trigger ?
  • Using a multi-meter – check for approximately 2.49V across the Detector “I” and “-” terminals on the controller.  This represents a normal closed circuit.
  •  

If all seems good but the problem persists:

  • Disconnect the smoke alarm circuit wiring from the 8-way green terminal on the controller and install a 4.7K resistor between the Detector “I” and “-” terminals on the controller.

This eliminates the smoke alarms and wiring.  If the problem persists it is likely a controller fault.  If the problem is solved, it is likely a problem with a smoke alarm or the circuit wiring.  Test plugs can be used to remove and bypass smoke alarms from the circuit.

The Controller will not reset

  • A red flashing LED indicator shows that the controller is not reset.
  • Is the controller Reset – green LED indicator on or flashing occasionally and no red LED indicator ?
  • Or is the controller Reset and the contactor not closed ?

The controller must see the 4.7K end-of-line resistor:

  • Have you installed the loop wire at the last smoke alarm ?
    • check the loop wire at the controller while you are at it.
  • Are the smoke alarms wired correctly ?
  • Has the jumper been removed for the last smoke alarm in the circuit ?
  • Do you see approximately 12V DC on the “+” and “-” terminals of each smoke detector ?  No voltage when hushed – press Reset.
  • Do you see approximately 12V DC between “+12” and the Detector “-” terminals on the back of the controller ?  This voltage should always be present.
  • Using a multi-meter – check for approximately 2.49V across the Detector “I” and “-” terminals on the controller.  This represents a normal closed circuit.
  • The isolated “I” input if left open will not prevent the controller from resetting.  If this input is closed it will trigger the controller when opened.  Voltage is applied “I” to adjacent “-” to close this input.  Normally used for a manual call-point.

If the controller is reset and the contactor is not activated or closed:

  • Is the contactor wired correctly ?
  • Does the contactor work ?  Disconnect the contactor wire at the controller and apply 230V AC to the contactor coil to test it.  Note:  DO NOT BACK-FEED the controller from the contactor.
  • The controller switches the P (phase)
  • Is the controller supplying 230V AC to the contactor coil ?
  • Has the 2.5A fuse on the back of the controller blown ?

Note:  Incorrectly wiring the mains Supply and Load can destroy the controller.  Connecting the mains supply across the two “N” terminals will blow tracks off the circuit board as these terminals are looped.

Unusual Faults

Contactor not releasing with TEST button

There have been a couple of reports of the contactor on the switchboard not dropping out when the controller is tripped using the test button.

Notes:

  • The contactor is a Normally Open (NO) type that is energized by the controller all the time.
  • The TEST button does exactly the same as activating a smoke alarm.  It is connected to and triggers the input on the controller that comes from the smoke alarms.
  • The controller uses a triac (electronic switch) to switch the phase (P) line to the contactor.  It can safely drive up to 500 watts.  The contactor at 2 watts or less is a very small load for the triac.  Triacs do not like loads with a very poor power factor – very inductive or capacitive.
  • Some contactors are no longer just a coil of wire acting as an inductive electro-magnet.  Some now include a rectifier and other components to drive the solenoid coil with a sort of bumpy DC.  The simple wire solenoid contactors may be the most reliable.
  • LED lamps are not good test lamps.  They contain an electronic power supply that has a very poor power factor and distorted current waveform.  The best test lamp is a good old 40W incandescent lamp in a holder with leads attached.  Check with your H&S department before doing anything that may involve wires and electricity.
  • Good luck.

On site test procedure:

  1. FAULT:  when fully installed, the contactor does not operate reliably . . . . . .
  2. Does the contactor not switch every time or sometimes ?  approx. how often ?
  3. Can the controller be reset to a normal state – green LED on, no flashing red LED ?
  4. Press and hold TEST button for a second or two.  Does the green LED turn to a flashing red LED ?  At this point the contactor should have switched off – if not . . . . . .
  5. Connect a contactor directly at the controller – a short cable.  Does it work ?
  6. Move the contactor back to the switchboard.  Does it still work ?
  7. Add a temporary additional load to the contactor (parallel) – a lamp, up to 100W, or a 10W+ LED lamp.  Should have the same effect connected at either end of the cable.  Does it now work ?
  8. Run a temporary cable from the controller to the contactor on the switchboard.  Could be a length of TPS on the floor.  Does it now work ?
  9. Try the temporary cable without and if necessary with the additional lamp load.  Any change ?
  10. If the temporary cable works but the installed cable does not – still thinking about this.
  11. Is there any load on the contactor during testing ?  Approximately how much load ?
  12. Note test results and report to Fire Preventors.  Include clear photos of the installation and wiring of the contactor and controller.

This test procedure attempts to identify the part or characteristic that causes the fault.  Is it the controller, contactor or installation.  It could be a combination of things – type of contactor making the controller switching marginal, possibly pushed over the edge by the installation, wiring or wire runs.

Alarm triggering when lights operated

The reported fault was that switching a room light on/off would cause the Fire Denyer to activate. It is not known whether from one particular lighting circuit or more than one circuit.  It is suggested that the controller was swapped and the fault persisted – suggesting it’s not a faulty controller.  Assuming the mains power is good, as it was not mentioned that other appliances caused the fault, we will assume that there is not something like a neutral fault.

To begin with we assume that the Fire Denyer system is correctly installed wired and powered.  This leaves us thinking that the lighting circuit is creating noise that is upsetting the FD controller.  Noise that could potentially trigger the controller could get in via the mains wiring directly or be coupled into the smoke detector circuit.

  1. The FD controller could be run on battery with the mains power feed disconnected from the controller, therefore no path to conduct noise in.  Does the fault continue or is it solved ?
  2. If the problem persists, the noise may be coupled into the smoke detector circuit.  Is the smoke detector wiring run close to and in parallel with the mains lighting wiring at any point over it’s length – it should not be.  Don’t run the detector wiring in ducting or directly along-side mains wiring.
  3. If the problem persists, disconnect the trigger circuit from the detectors (“I” terminal) but leave the 12V power connected to the detectors.  A 4.7K EOL resistor will have to be connected from the “I” terminal to -ve so thet the FD controller can be reset.  Does the fault continue or is it solved ?
  4. If the problem persists, also disconnect the 12V power feed wires to the detectors.  Does the fault continue or is it solved ?

Once you have eliminated the mains power supply and the smoke detector wiring, the problem should be solved.

If you find the mains power wiring is causing the problem, there is some quite serious noise on the mains and you may have a fault somewhere else in the home – faulty wiring, switches or appliances.

If the fault is caused only when the smoke detector wiring is connected, the wiring is probably installed or runs too close to mains wiring somewhere. It may be possible to solve this by installing a ferrite core on the detector wiring.

The fire Denyer Controller does have internal mains filtering and input circuit filtering components as well as code based filtering on inputs.

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