| Starting conditions
Note: - The Test Reports are presented for both versions of the prototype model (Version 1 and Version 2); with respect to starting conditions too. Our Electronic Ballast Technology uses “non pre-heat starting method” for starting the Tubular Fluorescent Lamp, and the compliance of the technology developed is checked as per the Standards by three tests viz:
1. Open circuit voltage measurements.
2. Ballast Impedance Test.
3. Cathode Current.
Starting conditions testing is considered as the most important test in the standards for evaluating the compliance and the compatibility of Electronic Ballast to the Tubular Fluorescent Lamp (TFL) it operates. Electronic Ballast being the complimentary product to the TFL it operates, determines the performance of the TFL in all aspects. Perfect compatibility between these two has to be achieved and this is a critical parameter that determines the optimum lamp and ballast life. The Indian standards for TFL's, IS 2418 (Part 2) : 1977, “Standard Lamp Data sheet”, which is derived by the Bureau of Indian Standards directly from the corresponding International Electrotechnical Commission Standards (IEC), namely, IEC publication 81 (1974), refers to the “Indian Standard Specification for Tubular Fluorescent Lamps for general lighting service”, and it specifies the performance requirements of Tubular Fluorescent Lamp's from 4 Watts to 80 Watts. The Standard specify that the principal method of lamp starting for all these different wattages lamps is the “pre-heated cathode starting” method only, and this is the method of starting used by Magnetic Ballast. Attention is drawn to the fact that the Tubular Fluorescent Lamp's performance criterions in the standards (both IEC and the Indian standards) have been formulated based upon its operation with Magnetic Ballast and not Electronic Ballast, as neither Electronic Ballast Technology nor the Standards for the same were in existence at the time of formulation of these Standards for Tubular Fluorescent Lamp's. Due to the many advantages of “non- preheat starting method” over “pre-heated cathode starting” (advantages like longer lamp life, least lamp failure etc to name a few), our Electronic Ballast Technology uses “non-preheat starting method” for starting the Tubular Fluorescent Lamp. We have perfectly synchronized “non pre-heat starting method” used by our Electronic Ballast (complying with the strict parameters of the Electronic Ballast and Tubular Fluorescent Lamp's standards itself), to start and operate the Tubular Fluorescent Lamp, which has been designed for, and uses “pre-heat cathode starting method”.
The operating frequency of the Magnetic Ballast is the supply line frequency itself, whereas for the Electronic Ballast, the operating frequency is a higher frequency, much deviated from the line supply frequency. Electronic Ballast's has numerous advantages over the contemporary Magnetic Ballast, and these advantages are translated into reality only when the Electronic Ballast perfectly synchronizes with the lamp it operates in all aspects. For this, compliance to the parameters of the starting conditions is the critical part.
The following data has been taken from the relevant lamp data sheet with reference to 40 Watt TFL
(We have taken 40 Watt TFL as “reference lamp” for the development of the Electronic Ballast Technology, due to reasons mentioned under the link “Electronic Ballast Technology”). The comprehensive lamp specifications as published in Indian Standards can be provided on request:-
As per TFL Data Sheet No.2418/1310-1: For 40 W TFL with starter type.
(Note:- Our Electronic Ballast does not require an external starter. Hence with respect to open circuit voltage, the minimum value at the starter is not taken into account).
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| Test report's explanations:-
1. Open circuit voltage measurements:- The Indian Standards for testing of Electronic Ballast for starting conditions (open circuit voltage test) says: “The open circuit voltage shall comply with the value as specified on the relevant lamp data sheet”.
“Note- In case or additional cathode heating during the starting process, lower values may be sufficient provided the glow discharge period does not exceed 100 ms”.
Open circuit Voltage (Peak):-Is measured at both 92% (211.6 V) and 106% (243.8 V) of the rated voltage (i.e., 230 V).
The mode of starting used by our Electronic Ballast is Non –Preheat starting mode.
The compliance of Electronic Ballast which uses “non pre-heat starting mode”, to TFL which uses “pre-heat starting mode” is the key that determines the longevity, durability and performance of the lamp-Ballast combination.
Complying these two different starting modes is the most difficult part when it comes to the development of the Electronic Ballast Technology.
Extracts from annex D of Clause 7 with respect to “Starting Conditions” of Electronic Ballast's [IS 13021 (Part 2): 1991] explains the vast difference in starting methodology under these two modes. In “pre-heat starting method” in Clause D.4.1 to D.4.4 of this annex, it is mentioned clearly that “low open circuit voltages is only required for starting as per this method, as there is adequate cathode pre-heating to ignite the lamp, either by means of current or voltage”. Whereas, in “ non pre-heat starting mode” as per D.4.5 of this annex “This method of lamp starting, takes advantage of the field emission that occurs at the unheated cathodes of a lamp when a high open circuit voltage is instantaneously applied across the lamp”. Annexure D-4.7 further says that “One of the major reasons for excessive lamp end blackening and subsequent early lamp failure is due to unduly high and/or long lasting glow discharge current during the starting process”. (“Non pre-heat starting mode” uses a high open circuit voltage instantaneously across unheated cathodes of the lamp, thereby instantaneously starting the lamp; thus avoiding repeated attempts at lamp starting as in “pre heat starting mode”. This further ensures that unduly high and/or long lasting glow discharging current does not get generated during the starting process. Thus excessive lamp end blackening and subsequent early lamp failure does not occur, which would otherwise occur when the lamp is started in “pre heat starting mode”).
Since the starting modes are vastly different, an amendment has been brought in the standards with respect to starting conditions for Electronic Ballasts with “non pre heat starting mode”, by the BIS, in terms of open circuit voltage parameters. With respect to Electronic Ballast with “non pre-heat starting mode”, “Amendment No.2 April 1994 to IS 13021 (Part 2): 1991 ac supplied Electronic Ballast for TFLs specification”:-Clause 7.3.1 “For lamps not covered by IS 2418 (Part 2): 1977, the peak value of open circuit voltage shall not exceed 700 V”. Such an amendment is applicable and very relevant, as the starting mode of the TFL's as per Indian Standards is “pre-heat mode” only, and there are no TFLs as per the Indian Standards {i.e. IS 2418 (Part 2): 1977}, which has “non pre-heat” starting mode i.e. the starting mode of the Electronic Ballast Technology developed and presented by us. Since there are no TFL's with “non preheat method” of starting, when our Electronic Ballast is used to start the TFL, the amendment automatically applies, as the TFL at that time is not covered under the purview of standards with respect to open circuit voltage. Note that in “non preheat starting mode” the starting process takes place with the application of high open circuit voltage across the unheated terminals of the lamp. This is the reason why such an amendment has been brought with respect to open circuit voltage under “non preheat starting mode”; for Electronic Ballast's which uses this mode of starting. Test circuit for measuring open circuit voltage as per the Indian Standards:
The value of the Non inductive resistors used (Rc) is 20 Ohms, 20 Watts as specified in the lamp data sheet, as equivalent resistors in place of each lamp cathode for 40 watt TFL. The standard parameter says “the open circuit voltage shall comply with the value as specified on the relevant lamp data sheet”. Minimum value (RMS) as per standards for open circuit voltage is not applicable as measurement is to be done at the starter as per the lamp data sheet, and our Electronic Ballast does not have a separate starter.
For version 1 the value of the maximum open circuit voltage (Peak) measured at 211.6 V is 388 V and at 243.8 V, it is 500 V. The maximum value of open circuit voltage permissible as per standards is 700 V (Peak).
The Open Circuit Voltage Oscillogram snap shots of version 1 are given below:-
For version 2, the value of the maximum open circuit voltage (Peak) measured at 211.6 V is 284 V and at 243.8 V, it is 300 V. In light of the lamp data sheet, attention is drawn to the upper limit value of open circuit voltage recorded for this version of Electronic Ballast with “non pre-heat starting mode”, and it can be noted clearly that the open circuit voltage readings totally complies with the requisitions of the open circuit voltage parameters of TFL with “pre-heat starting mode” as mentioned in the lamp data sheet. [i.e., as per lamp data sheet: Open Circuit Voltage: Minimum (RMS at starter- not applicable as the Ballast have a separate starter) = 180 V. Maximum (Peak) at lamp terminals = 400V.] Here total compatibility between the Electronic Ballast which uses “non pre-heat starting mode”, and the TFL which uses “pre-heat starting mode” is undoubtedly established, without the aid of the amendment as mentioned above (Above cited “Amendment No.2 April 1994 to IS 13021 (Part 2): 1991 ac supplied Electronic Ballast for TFLs specification”:- Clause 7.3.1 “For lamps not covered by IS 2418 (Part 2): 1977, the peak value of open circuit voltage shall not exceed 700 V ”) and thus, any ambiguity regarding open circuit voltage compliance with respect to starting conditions is removed. This is one of the most important parameters that determine the lamp life when it is operated with Electronic Ballast.
The Open Circuit Voltage Oscillogram snap shots for version 2 are given below:-
Ballast Impedance:-
The Indian Standards says: “With a non-inductive substitution resistor of the value on the relevant lamp data sheet substituted for the lamp, and at 92 percent of the rated voltage, the ballast shall deliver a current not less than the minimum value specified on that data sheet”.
Test circuit for measuring Ballast Impedance as per the Indian Standards:
The value of the Non inductive resistors “Rc” is 20 Ohms, 20 Watts as specified in the lamp data sheet, as equivalent resistors in place of each lamp cathode for 40 watt TFL. The value of the Non inductive resistor “R L ” is 40 Ohms 40 Watts as specified by the standards parameters as equivalent resistance for the lamp.
The minimum value as specified by the lamp data sheet for 40 Watt TFL = Pre-heating current: Minimum = 0.387 A. For version 1 the impedance current is 0.8 Amps and for version 2 the impedance current is 0.552 Amps. Here attention is drawn to annex D, Clause 7, Explanation of starting conditions in IS 13021 (Part 2): 1991, Clause D-4.6 “The level of open circuit voltage and the source impedance of the ballast determines the time, it takes for the lamp to pass through the glow current stage of the discharge to the full arc state”. The shorter this time, the longer will be the life of the lamp as one of the major reasons for excessive lamp end blackening and subsequent early lamp failure is due to unduly high and/or long lasting glow discharge current during the starting process. Here the Harmony between open circuit voltage and the ballast impedance ensures that the least amount of time is taken to “drive” the lamp rapidly through the glow current of the discharge to the full arc state. Thus our Electronic Ballasts provide optimum impedance current ensuring this, resulting in longer lamp life.
Cathode Current:-
The Indian standard says: “Ballasts of the non-preheat start type may supply some cathode heating during the starting. The cathode current, if any, shall not exceed the maximum value as specified on the relevant lamp data sheet. The measurement of cathode current is carried out with a substitution resistor, the value of which shall be calculated as follows:-
RI = 11(2.1 I n )-1
Where In =nominal value of lamp operating current”.
As per the lamp data sheet the nominal value of the lamp operating current is 0.430 Amps.
The R I used for testing 12.2 Ohms 20 Watts non-inductive substitution resistors as derived from the equation.
Test circuit for measuring Cathode Current under Starting Conditions as per the Indian Standards 
As per test parameters specified, measurement is done at both 92% (211.6 V) and 106% (243.8 V) of the rated voltage (i.e., 230 V). The maximum value as specified by the lamp data sheet for 40 Watt TFL is 0.904 A.
For version 1, the value of the cathode current measured at 211.6 V is 0.256 A and at 243.8 V, it is 0.165 A.
For version 2, the value of the cathode current measured at 211.6 V is 0.645 A and at 243.8 V, it is 0.826 A.
Here attention is drawn to annex D, Clause 7, Explanation of starting conditions in IS 13021 (Part 2) : 1991, Clause D-4.8 “ Some ballast may make use of currents in the lamp cathodes for the purpose other than adequate cathode heating (for example, for supporting starting with reduced starting voltages). In these instances, the limitations on maximum cathode current shall be observed to avoid cathode over heating”. The starting voltage (i.e. the voltage at which the lamp lights up and operates normally) of our Ballast Version 1 is 150 V and Version 2 is approximately 130 V. The maximum value of the cathode current is complied with respect to the both versions of Electronic Ballast. Thus compliance of starting conditions in totem for both versions ensures total compatibility between the lamp and ballast, thereby assuring longer life and performance for both.
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