.

Igniter
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Instruction Manual

Plant Name: CECON, Planta Concepcion, Paraguay

Contract Number: 1845027_900

Created by: VAH

Approved by: SKY
Approved date: 6-Jul-20

Doc. No.: 60193478 - 1.0

 

Instructions
Operation and maintenance

Plant name:&DOHUD5LVVR

Machine name: Igniter

FLS Equipment no.:

Purchase order number(s):


 

Table of Contents
Igniter ............................................................................................ 4


 

Igniter


Operation and Maintenance Manual

Igniter System comprising:

CA195 Premix Unit

J170E Torch
CU7/4B Control Unit

ICEL Ref: B9387

Customer: Kvisgaards Maskinfabrik / F.L. Smidth A/S
Order No. 950557 / 11406

Igniters Combustion Engineering Ltd.

Unit 6 Prospect Drive
Britannia Business Park
Lichfield
Staffordshire
WS14 9UX
England

Rev. 0
24.09.2019
Contents

Technical Data ......................................................................................................................................... 3

Reference Documents......................................................................................................................... 3
General Instructions................................................................................................................................ 3
J170E Ignition Torch ................................................................................................................................ 4
General Description ............................................................................................................................ 4
Installation Instructions ...................................................................................................................... 4
Commissioning Instructions ................................................................................................................ 5
Maintenance ....................................................................................................................................... 5
SA90 Encapsulated Coil ........................................................................................................................... 7
Purpose and Planning Information ..................................................................................................... 7
Operating Instructions ........................................................................................................................ 8
Technical Description .......................................................................................................................... 8
Installation or Removal ....................................................................................................................... 8
Maintenance Instructions ................................................................................................................... 9
Faultfinding ......................................................................................................................................... 9
CA195 Air-Gas Premix Unit ................................................................................................................... 11
Description ........................................................................................................................................ 11
Commissioning .................................................................................................................................. 11
Operation .......................................................................................................................................... 13
Service to Plant ................................................................................................................................. 13
Maintenance ..................................................................................................................................... 13
CU7/4B Control Unit ............................................................................................................................. 14
Drawings ........................................................................................................................................... 14
General Description .......................................................................................................................... 14
Operation .......................................................................................................................................... 14
Additional Features ........................................................................................................................... 14
System Fault Finding ............................................................................................................................. 16
Diode Probe Flame Testing ............................................................................................................... 18
Technical Data
Reference Documents
Drawings
A1/IG/13079 – J170E Torch
A1/IG/13080 – Premix Unit
A1/IG/13081 – CU7/4B Control Unit GA
A3/IG/13082 - CU7/4B Wiring Diagram

Hazardous Area Certificates

SA90 Encapsulated Coil – SIRA02ATEX5301X
Solenoid Coil – KEMA98ATEX2542
Pressure Switch – DEMKO09ATEX0815573X
Junction Box – SIRA04ATEX3131X

General Instructions
x The system provided must be installed in accordance with the drawings and instructions
provided.
x Preparation, operation and maintenance of the installation must be carried out in
accordance with the client’s current safety regulations and operating procedures.
x If there is any conflict with the drawings or instructions and the local site conditions and/or
regulations, then these conflicts must be resolved before installation and commissioning of
the equipment. Please contact ICE offices to advise any such problems.
x No changes may be made to the equipment or the operating procedures without the written
approval of ICE Engineering staff.
x The equipment is designed for ignition of a main burner when positioned inside the main
burner windbox, and the equipment must not be used for any other purpose.
x Commissioning and operation of the equipment must be carried out by trained and
experienced combustion engineers.
J170E Ignition Torch
General Description
The torch construction consists of a length of steel tube to one end of which is screwed a stainless
steel burner head. The other end of the mixture tube screws into a cross. An encapsulated is
attached to one entry of the cross and a hose adaptor is screwed into another entry. The remaining
entry is plugged. The front 500 mm section of tube can be removed for maintenance or
replacement.

A low tension pulse is fed into the encapsulated coil from the control unit and a HT spark occurs
across the gap between the spark electrode and the burner head.

A flexible hose connects to the hose adaptor and feeds a gas/air mixture into the torch for
combustion.

Note: The igniter may be withdrawn from the area of highest temperature in order to extend the
reliability of the unit. If this is adopted, it is very important that an operating procedure is generated
by the site to ensure that the torch is fully inserted into its correct operating position before
attempting to light the main burner. If the torch is not fully inserted, it is likely that a good igniter
flame will still be unable to light the main burner.

Installation Instructions
If the torch is over 3 m long it will be shipped in sections that must be assembled on site.

1. Socket the mixture tube sections together, and make a light weld to hold the sections
together. It is important that the weld does not interfere with the internal bore of the tube.
2. Remove the burner head from the front tube section, and install the conductor rod, using a
box spanner to secure the ¼” BSPT thread on the rear ceramic. Set the spark gap as
described below, and re-fit the burner head.
3. The HT cable must be connected to the front conductor rod section with the ring terminal.
Slide the length of heat shrink sleeve and insulating tube over the HT Cable. Fix the ring
connector to the threaded rod with locknuts to secure. Screw the insulation tube onto the
¼” BSPT nipple, and use the heat shrink sleeve to seal the HT Cable to the PTFE insulator
tube.

4. Position the end tube section by the front of the main tube length, and feed the HT cable
through the mixture tube (e.g. using a rod to push the cable or blowing the cable with
compressed air etc.). When the cable is all of the way through the mixture tube, screw the
front tube section onto the main tube. The HT cable will twist within the tube, but this is not
a problem.
5. Secure the loose and of the HT cable to the lead thro assembly.
Commissioning Instructions
For the purpose of testing, the equipment should be set up in accordance with the appropriate
installation drawings. The torch should be mounted outside the burner register in a safe area with all
hoses and electrical connections made, and in such a position that the pilot flame can be viewed.

WARNING: All local and statutory safety regulations must be strictly observed.

Ignition Spark Only Check

Turn 'OFF' the gas and air services to the premix unit.

Initiate control unit.

Sparking should take place between the end of spark electrode and the front face of the burner
head. If this is not the case, it may be necessary to adjust the spark gap; this can be achieved as
follows:

1. Switch 'OFF' mains supply to the control unit

2. Secure the barrel of the pilot torch, depress the short leg of the electrode towards the
centre of the burner head and unscrew the head from the mixture tube.
3. Release the electrode lock nut and screw electrode clockwise to reduce the spark gap and
anti-clockwise to increase the gap. Correct gap is between 2.5 and 3.5mm. As a guide to
adjustment, with the burner head off, the dimensions between the open end of the
electrode and the end of the mixture tube should be 28 mm.
4. Tighten the electrode lock nut and refit the burner head. Check gap is correct. It is desirable
that the sparking end of the electrode be oriented between two of the flame retention holes
in the head. This sparking end should also be uppermost in the burner head when the torch
is in its operating position.
5. Close mains switch and operate 'START' button to check sparking.

Maintenance
Since there are no moving parts, routine maintenance consists of general tightness of fittings and
connections and ensuring that the conductor rod insulators within the torch mixture tube are clean
and moist free.

Routine maintenance procedure is as follows:

Ensure that all services are switched 'OFF'.

Disconnect cable assembly, flexible mixture hose, slacken torch mounting and carefully remove
torch igniter from the burner guide tube.

Dismantling
Clamp torch in suitable vice taking care not to damage the tube.

Remove plug to expose HT connection to lead-thro-assembly and remove M5 nut to release HT

cable.

Unscrew front end on mixture tube. If there is no damage to the HT cable, it is recommended that
this is left in position along the length of the tube and the connection to the front Conductor Rod
section is dismantled.
To remove the conductor rod from the front tube section, first depress short leg of spark electrode
towards centre of the burner head, and unscrew the burner head from mixture tube. Unscrew the
electrode from the 5 mm conductor rod. Next, use a box spanner to unscrew the ¼” BSPT nipple
(cemented to the rear ceramic insulator) from the tube support disc. The conductor rod may now be
removed.

Re-Assembly
Reassemble in reverse order to dismantling.

Before fitting burner head adjust the position of spark electrode as described in the commissioning
instructions.
SA90 Encapsulated Coil
Purpose and Planning Information
Rating: IIC T6
ATEX Category:
II 2 G
Ambient temperature (max): +60°C (fixed or flexible)
Ambient temperature (min): Installation Type
Cable type Min Bend Radius Fixed Flexible
SY 20 x dia -25qC 0qC
SWA 6 x dia -35qC Not Applicable
Silicone (with steel overbraid) 20 x dia -50qC -50qC
HOFR 8 x dia -20qC -20qC
RFOU 8 x dia -50qC -20qC

Input voltage: 175V DC pulse cycling at a nominal 50 Hz

Output voltage: 8750 V DC pulsing at frequency of input
Certificate number: SIRA 02ATEX5301X

This equipment must not be installed in locations where substances that may attack the materials of
construction are present. The unit contains the following materials:

Cable (outer sheath) PVC

Cable gland Brass
Casing and snout Zinc plated mild steel
Label Aluminium
Nut Brass
Insulators PTFE or Nylon

Before installation, ensure that these materials are compatible with the location. Contact the
manufacturer for more information.

Special Conditions for Safe Use

The following conditions of safe use apply to the encapsulated coil:

x The electrical input to the coil must only be supplied by a pulsing unit as specified by the
manufacturer. This produces a pulsed DC low voltage supply, which has a nominal peak
voltage of 175V at a limiting current of 250 mA (protected by a 250mA fuse). This 250mA
fuse has a 35A breaking capacity.
x The unit is suitable for fixed installation between ambient temperatures of -50qC and +60qC
or flexible installation between ambient temperatures of -50qC and +60qC subject to cable
specification, see Purpose and Planning section.
x The pulsing unit must be situated in either a suitable ATEX approved hazardous area
protective enclosure or in a non-hazardous area.
 x The supply lead must be suitably terminated and protected for use in a hazardous area or
connected in a non-hazardous area.
x Do not connect or disconnect the quick release connector when energised in a hazardous
area.
x The cable shall not be subjected to bends that are more onerous than the values listed in tha
table above.
x Do not energise with the quick release connector separated.
x Minimum cable installation temperature is limited to 0qC for Steel Wire Armoured cable.
x The quick release connector must only be connected to the mating parts fitted to the fuel-
burning apparatus, as shown in the certified drawings.

Operating Instructions
Before operating the encapsulated coil ensure:

1. The encapsulated coil is correctly mounted in accordance with the appropriate drawings
supplied with this manual.
2. The special conditions of safe use, listed above, are met.

Refer to appropriate control-unit operating instructions to energize the encapsulated coil.

Emergency Shutdown
There are no special emergency shutdown procedures for the encapsulated coil or the igniter
system. See instructions for host equipment for emergency shutdown instructions.

Technical Description
The encapsulated coil provides a pulsing high voltage (HT) output when supplied with a low voltage
pulse from an appropriate control unit. The high voltage output may be used to create a spark across
a gap of up to 8mm. The input pulses at mains frequency, making the resultant spark appear
continuous. The primary and secondary windings are linked to enable the encapsulated coil to pass
an A.C. voltage for flame detection by flame rectification when connected to a suitable control unit.

The encapsulated coil is designed and manufactured in accordance with the requirements of ATEX
Directive 94/9/EC enabling it to be used in hazardous areas. It is rated IIC T6. It can be used where
the explosion hazard is from gases of the IIA, IIB or IIC ranges.

There are several models of the encapsulated coil, the differences being in the electrical termination
and mounting arrangements. All other features are common to all encapsulated coils.

Encapsulated coils consist of a metal casing into which a coil is encapsulated with epoxy resin. A
supply cable runs through a cable gland into one end of the tube. The cable is permanently
encapsulated into the coil during manufacture and cannot be removed. A variety of cable types may
be used. At the other end of the tube is the output connection and mounting fittings.

Installation or Removal
The encapsulated coil must be de-energized and in a safe area when installed or removed.

Install the encapsulated coil in accordance with the relevant wiring diagram and general
arrangement drawing. Wiring shall comply with local and national regulations. Installation shall be
carried out by competent and trained personnel.

Protect the encapsulated coil from damage and water ingress.

The cores of the supply cable may be either numbered or coloured depending on the cable type. See
Table 1 and the appropriate wiring diagram for details of core identification.

Storage
Store the encapsulated coil in cool and dry conditions such that it cannot be damaged.

Maintenance Instructions
CAUTION
x ONLY DISCONNECT THE ENCAPSULATED COIL WHEN IT IS DE-ENERGIZED AND IN A SAFE
AREA.
x DO NOT ENERGISE A DISCONNECTED ENCAPSULATED COIL.

Keep the encapsulated coil and the HT connections clean and dry to prevent breakdown and
flashover of the high voltage supply.

Identify a faulty encapsulated coil as described in the fault-finding section. Do not attempt to repair
an encapsulated coil under any circumstances otherwise its explosion-proof properties will be
invalidated.

If the fuse on the control unit fails, replace it with a 250mA fuse (type T) that has a 35A breaking
capacity.

Faultfinding
CAUTION
x ONLY DISCONNECT THE ENCAPSULATED COIL WHEN IT IS DE-ENERGIZED AND IN A SAFE
AREA.
x DO NOT ENERGISE A DISCONNECTED ENCAPSULATED COIL.

Refer to Figure 1. To identify a faulty coil:

Disconnect the encapsulated coil from the control-unit and check the resistance of primary winding
by connecting ohmmeter between cores A and B of the supply cable. Resistance should be
ĂƉƉƌŽdžŝŵĂƚĞůLJϬ͘ϲɏ͘

Check resistance of secondary winding by connecting ohmmeter between core A or B and the HT
ŽƵƚƉƵƚ;yͿŽĨĞŶĐĂƉƐƵůĂƚĞĚĐŽŝů͘ZĞƐŝƐƚĂŶĐĞƐŚŽƵůĚďĞĂƉƉƌŽdžŝŵĂƚĞůLJϲϬϬɏ͘

Oil and debris around the HT output of the encapsulated coil may cause the high voltage to flashover
to earthed metalwork. Clean accumulated debris with clean dry rag.

Damaged insulation around the HT output of the encapsulated coil may cause the high voltage to
flashover or breakdown to earthed metalwork. Replace the encapsulated coil or return to Igniters
Combustion Eng. Ltd. Do NOT attempt to repair the encapsulated coil yourself otherwise the
protection will be invalidated.
Figure 1 Coil internal circuit.

Table 1 Core Identification Cross Reference

Encapsulated Coil Terminations (see Figure 1)

A B C
Identification

Brown Blue Green /Yellow

Core

Brown White Green

Red Blue Yellow
1 2 3
CA195 Air-Gas Premix Unit
Description
This unit provides a regulated mixture of gas and air to the torch via the flexible mixture hose.

An electrically operated solenoid valve opens to permit air to flow through a pressure regulator into
the mixer; at the same time a solenoid valve (2 in the case of double block systems) opens, allowing
gas to flow through a pressure regulator to the mixer where it is entrained with the air.

A junction box mounted on the base-plate provides a convenient point for the cable from the control
unit to the solenoid valve and the torch.

Normally the premix unit should be mounted 2m to 3m from the torch.

A differential pressure switch is built into the mixer assembly, set to sense the pressure of the gas as
it enters the air-gas mixer. This is designed to prevent the CU7/4B Control Unit providing a flame
relay output signal for ‘Igniter On’ unless there is a minimum gas pressure detected by the pressure
switch. This switching pressure is adjustable via the screw accessible inside the junction box. The
purpose of the pressure switch is to prevent an operator adjusting the igniter flame to be (for
example) 2 cm long. Such as small flame would still be detected by the detection system, but would
clearly be unsuitable for ignition of a large kiln burner. The pressure switch interlock confirms that a
‘reasonable’ minimum gas pressure is supplied to the torch, which will provide a flame which is
suitable for burner ignition.

The air valve is drilled with a 2 mm purge hole to provide a low volume purge air flow when the
igniter is switched off and the air valve is closed.

Commissioning
Air and Gas Supply Pressures
Air Pressure : Minimum : 60 PSIG
Maximum : 115 PSIG (DC Valves)
: 140 PSIG (AC Valves)
Recommended : 80 - 100 PSIG (500 - 700 Kpa)
Gas Pressure:

The premix unit can be manufactured to cater for virtually any gases and supply pressure from 4"
w.g. to 100 PSI. The solenoid valve, the pressure regulator and the fixed jet orifice will be sized to
suit the gas and the stated supply pressure range.

Recommended Premix Pressure Regulator Settings

Gas Gas Pressure Air Pressure

Propane 8 PSIG 20 PSIG

Natural Gas 12 PSIG 20 PSIG

Pressure Back-Loading
The air and gas pressure regulators are back-loaded to the mixture pressure in the air-gas mixer
assembly.

If a long pipe-run is involved for the air-gas mixture between the premix unit and the torch, it is
possible for considerable back pressure to be generated in the air-gas mixer assembly. This will be
increased further by additional bends or restrictions in the pipe-work. The back pressure will tend to
reduce the flow of air and gas into the mixer block; however, with the back-loading connections, the
increase in mixture pressure is exactly matched by an increase in the air and gas supply pressures.
Thus, the actual volume flow of air and gas into the mixer remains the same, and the quality and
stability of the igniter flame is maintained.

Mixture Adjustment
NOTE: Adjustments should only be made with a constant ignition source on the igniter.

NOTE: When the caps on the top of the pressure regulators are removed, there will be a very small
leakage of combustible air-gas mixture via the pressure adjustment screw. Always make sure that
the top cap is replaced after pressure adjustments.

Slacken the locknut on air pressure regulator, initiate burner control to cycle and if necessary reduce
air pressure indication to the lower of the recommended pressures.

Gas pressure is factory pre-set and should normally require alteration.

Initiate the ignition cycle, if necessary slowly reduce the gas supply by turning the needle clockwise;
alternatively increase by turning anti-clockwise.

When stable flame has been established final adjustments can be made with the flame live as
previously described.

Check that pilot ignition can be re-established consistently with the final adjustments. If re-ignition
cannot be made, gradually reduce the air pressure.

Finally, lock the air pressure regulator taking care not to disturb the final adjustment.

NOTE: Increasing air pressure will weaken flame; reducing pressure will enrich the flame. Increased
gas pressure will enrich the flame; reducing pressure will weaken the flame.

Switch control unit 'OFF' and after a few seconds delay, re-initiate the complete cycle to confirm the
adjustments.

NOTE: Ignition of the mixture is positive and the flame is hard and stable.

Periodically check the regulated air and gas supply pressures are steady.

Switch unit 'OFF' and close master supply valves to system. The pilot torch should now be fitted to
this correct position relative to the burner. The equipment is now ready for operation.
Operation
WARNING: All local and statutory safety regulations must be strictly observed.

Service to Plant
1. Ensure air and gas supplies are adequate in delivery lines to the premix unit.
NOTE: It is recommended that the air lines are fitted with a moisture trap to avoid problems
with ignition electrode assembly.
2. Delivery line master control valves closed.
3. All flexible supply lines and cables connected.
4. Electrical isolator off, mains supply available.
5. Open delivery line control valves to supply gas and air to the premix unit.
6. Switch on electrical supply to the control unit.
7. Operate the START button or control switch to energise the control Unit. The 'Pilot on' lamp
will light (if fitted) confirming that the pilot flame is established.
8. The 'Pilot On' lamp (if fitted) will indicate that the pilot flame is present and is being
monitored.
9. The main flame control circuit contacts will energise.
10. To shut down the system, operate the Stop button or control switch to de-energise the
control unit. Shut all manual valves fuel and air.

Maintenance
Providing the air and gas services directed to the premix unit are clean and dry, routine servicing can
be confined to regular inspection of pipe connections and fittings and checking particularly for gas
leaks.

For major overhaul and component replacement it is recommended that the complete premix unit
can be removed as follows:

1. Power off and depressurise the unit.

2. Disconnect air & gas service connection.
3. Remove mixture hose connection.
4. Disconnect external cable assemblies from junction box.
5. Remove four fixing supporting back plate, complete unit can now be withdrawn.

Regular Maintenance
Little or no maintenance to the regulators is necessary providing the services to the units are free
from dirt and moisture.

Before maintenance is attempted, the respective supplies should be switched 'OFF' and pressure on
the unit diaphragm should be released through the adjustment wheel.
CU7/4B Control Unit
Drawings

General Description
The CU7/4B provides a continuous medium voltage, medium current oscillating pulse signal, which,
when applied to the correct type of coil will produce a continuous spark for ignition purposes. The
controller also operates the gas control valve and monitors the presence of the flame once the
ignition sequence is complete.

Operation
Select the switch on the PCB to 110/240v AC as appropriate and connect the mains supply voltage.
The yellow "POWER" LED will light.

Spark Mode
On models fitted with local control press the "START" pushbutton. On detection of the spark the red
"SPARK" LED will light, and the pushbutton can be released (approx. 0.5 seconds).

On models operated by remote control the spark is initiated by closing external contact between
terminals 5 and 6 (Earth). This may be done manually or by a relay circuit.

The presence of the spark is detected, indicated by the red "SPARK" LED, and relay RL2 is energised
opening the pilot gas valve.

The spark initiate signal may be maintained, or terminated after approximately 1 second, as the
internal timer circuit controls the spark time of 4 seconds.

Flame Detection
When the spark is terminated the control automatically switches to flame detection and the flame is
monitored as indicated by the green "FLAME" LED. Relay RL2 remains energised and maintains the
pilot gas valve open, and operates two N/O-N/C contacts which can be used for external indication.

NOTE that the green ‘Flame’ LED dims in intensity every few seconds, as the internal circuit goes
through its self-checking sequence. This is a normal part of the system operation.

Relay RL2 de-energises approximately 0.5 second after the spark ceases if the flame detection circuit
has not seen the flame. The pilot gas valve will close at this time.

Additional Features
The CU7/4B control provides a connection point for a flame current meter to be fitted either
permanently or temporarily for commissioning purposes. The link between PCB terminals E3 and G1
should be removed, and the meter connected with the Positive Terminal connected to Terminal G1.

NOTE: If the meter is not used, terminals E3 & G1 must be linked or the flame detect circuit will not
operate.

Consult Igniter's Works for information about locating the flame signal meter over 3m away from
the PCB Assy.

A flame sensitivity switch is provided with NORMAL and HIGH sensitivity settings. For all standard
applications the NORMAL setting should be used. In situations where long cable runs are required
between the control unit and the pilot torch, or other factors cause loss of flame signal then the
HIGH setting should be used.

There is no advantage is using HIGH, sensitivity setting for installations where the NORMAL
sensitivity settings will suffice.

A PERMANENT SPARK switch is provided which by-passes the spark timer circuit and enables a
permanent spark to be provided for commissioning purposes. The spark detect relay RL2 is activated
in the normal way and the valves are open during permanent spark operation.

NOTE that the spark starts, and the valves open (if connected) immediately the ‘Permanent Spark’
switch is operated.

Self-Checking Circuit
The CU7/4B continuously checks the flame detection circuits for a fault that would indicate a flame
is on when the flame is actually not present. If the self-checking circuit finds such a fault in the
circuit, the valves are closed and the output to the main burner circuits indicates ‘Pilot Off’. The fault
circuit lights a red LED on the PCB.

Note that the self-checking circuit causes the green ‘Flame On’ LED to dim in luminance every 3
seconds. This is normal and is not an indication of a problem.

Notes

Ensure that operators to not touch the back of the PCB during handling, as this may damage one of
the IC chips.

It is important that the polarity of the cable connections between the control unit & the ignition coil
are made correctly; otherwise the unit will not operate correctly, and the flame detection will not
function.
System Fault Finding

Symptom or Fault Tests & Diagnosis

Important Note: When testing the spark only, or electronically testing the flame detection circuits, it is
necessary to ensure that the air & gas supplies are isolated with manual valves. This will prevent air &
gas entering the system if the valves should open during testing.
Torch fails to The spark is occurring inside the torch tube. Strip down the torch and look for a
spark at the tip, damaged insulator or a source of tracking along the insulator surface, e.g. moisture
but the ‘Spark’ or carbon deposits. Clean and dry the rod, and re-test.
LED lights on the
Control Unit
Torch fails to The problem could be with either:
spark, and the
A faulty ignition coil
‘Spark’ LED does
not light. A short circuit on the torch, e.g. earthed electrode
Incorrect wiring to the control unit.
A PCB fault
A power supply transformer fault
If the spark gap is less than 1 mm, the spark may not be detected
Test for Ignition Measure resistance of the coil:
Coil:
ohms between two primary winding cores
600 ohms between primary winding core and the HT output.
Primary winding on encapsulated coil between the two non-earth cores (brown &
blue, or red & blue). Secondary winding on encapsulated coil between blue core &
HT connection.
Test for torch Take torch apart, and check for short circuit and size of spark gap - should be 2.5 to
assembly 3.5 mm
Test for PCB Fault Ensure that the PCB voltage selector switch is in the correct position.
Since the spark output signal is a pulsed capacitor discharge, a normal multimeter
will not record a meaningful voltage for the signal to the coil with the coil
connected, and the output may only be checked with an oscilloscope. If this is
available, the output should be 150V DC peak pulses, cycling with the mains power
frequency.
Test for Power The voltages that should be present on the transformer windings are shown on the
Transformer Fault wiring diagram. These may be checked with a multimeter.
The torch sparks If the spark gap is too small, i.e. 1.5 mm or less, there may be insufficient power to
but fails to light light the flame.
Are both the air & gas supplies available at the correct pressures?
The air-gas ratio may be incorrect - see premix unit manual section
The torch burner head may be damaged, or the flame retention holes blocked,
preventing the flame from stabilising.
 The mixture hose may be damaged so that the air-gas ratio is affected by an
increased back pressure. See premix section about long pipe runs to see the effect
of increased back pressure.
The air or gas jets in the mixer may be blocked.
Symptom or Fault Tests & Diagnosis
The torch lights, Possible causes:
but fails to detect
The ignition coil may be damaged: if there is a break in the secondary winding, the
the flame
spark may still occur, but the low voltage (150 V) flame detection signal will not
jump the broken connection: see coil check.
The electrode may not be positioned in the flame, i.e. it is centralised in the burner
head - it should be within 3-4 mm of the side wall of the burner head. It must be in
the flame to detect.
A fault with the PCB on any of a number of component parts.
The cable run from the control unit to the torch may be causing too many losses.
Try the ‘HIGH’ flame sensitivity setting. Cable runs over 15 m should be in at least
1.5 mm2 cores. Check the flame signal level.
Is there a Burner Management System that is shutting the igniter down before the
flame signal is established? The flame signal is not generated until approx. ½
second after the spark stops.
The torch lights Is the main burner air, in which the torch is positioned, preheated to a high
and detects the temperature? It is possible for the tube & conductor rod to expand by several mm
flame, but shuts when the torch is off, sitting in the hot air flow. Since the tube and conductor rod
down after a grow by the same amount, the spark gap remains correct, as when the torch was
short time set-up at ambient temperature. When the torch is lit, the flame is initially
detected, but the cold air-gas flow over the conductor causes the rod to shrink,
and may cause the electrode to be shorted-out against the burner head. In this
case, an immediate re-start attempt will also fail.
The remedy is to set a much larger spark gap (e.g. 10 mm) between the end of the
electrode & the flat face of the burner head, and to set the spark gap as 2.5-3.5
mm to the side wall of the burner head.
To check flame Manufacture a ‘Diode Probe’ with a 400k ohm resistor soldered to a diode. Solder
detection a short (10 cm) piece of wire to each end of the chain. Place the end nearest the
electronically diode cathode to earth (e.g. burner head wall), and touch the anode end onto the
electrode after a spark attempt, within 0.5 seconds of the spark stopping. If the
diode probe is placed close to the electrode during the spark period, it will be
damaged by the spark.
The diode probe may be used directly onto the terminals of the PCB, touching the
anode onto the terminal for the ‘Blue’ wire to the ignition coil. It may be that the
diode probe gives flame indication on the PCB with the coil wiring disconnected,
but does not work, when the coil wiring is connected. In this event the problem
lies with either the torch, the ignition coil or the interconnecting cabling.

B
Diode Probe Flame Testing

a) remove the pilot from the heater, and use the probe on the electrode, with the
earth end on the burner head body or the mixture tube.

If it detects, then all the electronics & ignition coil is OK, and the problem must be the
quality of the flame in the pilot tip or the position of the electrode in the tip.

b) If the diode probe does not work on the electrode, disconnect the SA90 ignition
coil, and use the probe between earth & the recessed screw head inside the top of
the coil. If the unit now detects, then the problem lies with the torch.
c) If there is no detection on the SA90 coil, use the diode probe on the terminals of
the PCB, where the blue core & earth come back from the ignition coil.

If no detection, remove the cores of the ignition coil cable from the terminals, and
retest on the PCB. If still no detection, the problem must be with the electronics.