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Standard Test Method for Dispatching Telephone Switchboard of the Ministry of Electronic Industry of the People's Republic of China
SJ 2784-87
This test is based on S2783-87 and is mainly applicable to the dispatching telephone switchboard special communication equipment used for dispatching command in fixed facilities on the ground. 1 Test conditions
Relative humidity,
Atmospheric pressure:
2 Performance test
15~35,
45%±5%
86106kPa.
2.1 Test of basic performance
Test 3.2~3.10 of 1 in SJ2783-87 item by item according to the specified working conditions, and the test results should meet the requirements.
2.2 Performance test that can be set as needed
Test 4.1~4.8 of SJ2783-8711 item by item according to the specified working conditions, and the test results should meet the requirements.
Technical standard test
Test 6.1~5.8 and 6.2~6. in SJ2783-87 item by item according to the following provisions, and the test results should meet the requirements.
8.1 Test of line parameters
1.1 Direct line loop resistance
3.1.1.1 Test equipment
Main current milliammeter: measure the maximum range 1~100mA, error ±2.0%. 。 .1.1.2 Test method
Wire as shown in Figure 1
R loop maximum 9%
Make, closed, DC milliampere reading should not be less than 18㎡A. Issued by the Ministry of Electronics Industry of the People's Republic of China on April 6, 1887. Implementation on October 1, 1987. 3.2. Insulation resistance and capacitance between user lines
Wire as shown in Figure 2
$J2T84—-87
R loop maximum = 300+0:%%
R in the figure
Electronic research
The dispatch telephone switchboard should be able to normally receive the call signal of the direct-through user and call the direct-through user with the ring signal, and have normal conversation with the user.
3.2 Test of transmission loss
3.2.1 Test equipment
Audio oscillator, balanced output, divided into 0 and 600 gears. Frequency range 300~3400Hz.
Output level range -40～+20dB.
Frequency selection level, balanced input, impedance greater than 10k. Frequency selection range 50Hz~10kHz.
Measurement level range -80～+20dB.
Balanced attenuator, frequency range should be greater than 300~3400Hz. Attenuation value 0~2d, error ±002dB.
Characteristic impedance 600%.
Transmission coil: turns ratio is 1:1.
3.2.2 Test method
Test by comparison method. 。
Connect according to Figure 3
SJ 2784-8#
Term user
a. Any user is connected to the dispatcher, and the audio oscillator sends a frequency of 800Hz and a 0dBmO level signal. b. Turn the switch to the side of the measured call loop, take the level meter reading, and then turn the switch to the balanced attenuator side, adjust the attenuator so that the level meter reading is consistent with the reading at the end of the measured call loop. At this time, the attenuator value is the transmission attenuation value of the call.
3,3, Crosstalk attenuation test
3.3.1 Test equipment
Audio oscillator, frequency selection level meter, and transfer coil are all in accordance with 3,2.1. Balanced attenuator, frequency range 300～3400Hz. Attenuation value 10～96dB, error ±0.2dB. Characteristic impedance 600Ω.
8.9.2 Test method
Test by comparison method.
Wire as shown in Figure 4
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a, connect any two pairs of adjacent telephone loops as the main string loop and the passive loop, and terminate the main and passive loops with 600V.
b. At one end of the main string loop, the audio oscillator sends a 1100Hz signal, adjust the balanced attenuator to 0dBmO, and adjust the audio oscillator output so that the frequency-selective level meter reading is 11.4dBmO. c, turn the switch to the passive user loop end, take the level meter reading, and then turn it back to the balanced attenuator side, adjust the attenuator so that the level meter reading is the same as the reading at the passive end. At this time, the attenuator value is the crosstalk attenuation between the two pairs of adjacent telephone loops.
3.4 NoiseWww.bzxZ.net
3.4.1 Test equipment
Noise meter: Test frequency 15Hz～20kHz. Measurement range 0.3mV, measurement error less than ±5%. Stability less than ±2% within 8 hours.
Input impedance = 10k.
3.4.2 Test method
The power supply of the dispatch telephone switchboard is not floating. Dial the line according to Figure 5
60039Ri
$12784-87
Measure the tenant's information circuit
Shundu Fengzhi Electromechanical
60 Mengt30
4±044F
aAny user connects with the dispatcher, at this time, another dispatcher sends a ring current signal to a user. b. At the ab end or a'b/end, use a noise meter to measure the busy-hour noise level of the network with and without counterweight. 3.6 Unbalanced to ground
8.5.1 Test equipment
Same as 2.1 (except balanced attenuator).
3, 2 Test method
Test on the reverse loop.
Connect the network according to Figure 6
a. Any user and the dispatcher are the calling and called. After the call is connected, cut off the external line of the calling and called ends. b. First measure the balanced attenuation of the resistance bridge circuit. Its balanced attenuation should be greater than 66dE when it is grounded or not grounded at point A.
c, connect to the measured call loop, the frequency of the high frequency oscillator is 300, 400, 600, 800, 1000, 1600, 2000, 3000, 3100Hz, the value of 0dB, and the unbalanced attenuation value of point A grounded and ungrounded at each frequency is respectively obtained. 3.6 Ringing current
3.6.1 Test equipment
AC meter: It should be able to measure the effective value of the signal voltage measurement range of 15~60HIZ, 1200V, and the error is not more than 2%. The input impedance should be less than 10k (unbalanced). Meter for measuring frequency: Measuring the signal frequency in the range of 10~100Hz, the measurement error is not more than ±0.1Hz. The instrument for measuring the time of the ringing current can measure the duration of the pulse and the interval between various step pulses. The measurement range is 100mS~10S, and the measurement error is not more than ±10mS. 8.6.2 Test method 3.6.2.1 Measurement of the frequency of the ringing current source Use the instrument for measuring the frequency to measure directly at the output end of the ringing current generator. 3.6.2.2 Measurement of the output voltage of the ringing current source Connect the wires according to Figure 7 and perform empty measurement. (250) Low-voltage pure current Select the low-voltage pure current Use an AC voltmeter to measure at the output end of the ringing current generator. The effective value of the ringing current output voltage should be 90±15V. Connect the wires according to Figure 8 and perform full-load measurement.
20（2）
Difficulty in producing circuit
(250%)
Some reverse sources
Included:
Home:
About circuit, etc.)
Wiring
Electrical output
(R maximum solution%
First, actually call a user, keep the called party ringing, and simulate full load (such as
) at the output of the current generator. Figure 8 shows the wire part), then at the called user wiring terminal (R loop maximum +3kα) add a positive (series current capacitor 20μF), cut the external line, control the ringing circuit to make the ringing signal continuous, and use AC voltage attenuation to measure the ringing current voltage on the load (R group maximum +3k?) and the output end of the ringing current generator. ZL is the equivalent load of each line, which should include the load of the total distribution rack of the ringing current barrier (calculated according to the actual circuit) and the load of the total distribution rack to the user.
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The load of the user (measured as 3.4k pure resistance), n is the maximum number of channels ringing at the same time. 3.6.2.3 Intermittent time measurement
The ringing intermittent time should be measured on the logic circuit that controls the intermittent. 3.7 Buzzer signal
3.1.1 Test equipment
·The instrument for measuring frequency, the signal frequency of the measurement range is 200～3000Hz, and the tidal error is not more than 1Hz. The instrument for measuring time is still 3.6.1
Millivoltmeter, should be able to measure the effective value of the signal voltage of 200~3000Hz. The measuring range is 10mV～300V, and the impedance should not be less than 100k9.3.7.2 Test method
At the input end of the buzz signal, measure the frequency and power of the buzz. The duration of the buzz should be measured on the logic circuit that controls the discontinuity.
3.8 Main point level of the amplification system
3.8.1 Test equipment
Audio oscillator, balanced output.
Frequency range 20Hz200kHz.
Non-linear distortion①Voltage output: When the output is 5V, 20Hz～20kHz≤0.2%. ②Power output: When the output is 4W, 20Hz～20kHz≤1%. Frequency-selective level meter, same as 3.2.1
millivolt meter, same as 3.7.1
distortion tester, distortion temperature accuracy: soil 10% (full scale) ±0.01% (20Hz～200kHz). Input range: unbalanced, 300V~300V balanced, 300mV~10V
8.8.2 Test method
3.8.2.1 Intercom amplification level
#, send
wire according to Figure 9
audio#
send micro branch
receive micro branch
SJ 2784—87
Jiang Jieshu
service user electricity fee
fuzhenshuang meter
At the microphone jack end of the dispatch telephone switchboard, send the specified 800Hz signal level, and at the user's second line end, use a level meter to measure the output level.
b. Receiving
Connect the wires as shown in Figure 10
Sending branch
Receiving branch
Distortion meter
Connect the grid
Use branch
Figure 10
At the user's second-line end, send a 6.5dBmO, 800Hz signal, and use a millivoltmeter to measure the output power of the switchboard speaker.
3.8.2.2 Simulcasting level
Connect as per Figure 11
Moving device
In the figure: ZL-600
is a product for simultaneous remote control
$J 2784—87
Electricity
(coea)
Send the specified 800Hz signal level at the microphone jack of the dispatch telephone exchange, and use a level meter to measure the output level of the panel at the user's second line.
8.8.2,9 Frequency characteristics
Connect as per Figure 9 and Figure 10.
Adjust to the rated output value at 800Hz, then keep the input unchanged, change the oscillator frequency, and measure the output signal level at each corresponding frequency point. And compare it with the output level at 800Hz. $.8.2.4 Nonlinear distortion coefficient
Connect as per Figure 9 and Figure 10.
At the input end of the sending and receiving branches, send the signal level specified at 800Hz, and measure it with a distortion meter at the output end. 4 Safety performance test,
4.1 Dielectric strength test
The test voltage is a 50HIz sine wave with cross-filtering. The power of the test power supply should not be less than 0.5kv·A. A 1500V (effective value) test voltage is applied between the AC power input end and the casing of the dispatch telephone switchboard for 1min. There should be no flying or breakdown during the test.
4.2 Measurement of insulation resistance
This test is carried out after the dielectric strength test. A megohmmeter with a true current voltage of 500V is used to measure the insulation resistance between the AC power input end of the dispatch telephone and the casing. A megohmmeter with a DC voltage of 250V is used to measure the insulation resistance between the DC power input end and the casing of the dispatch telephone switchboard.
Additional Notes,
SJ 2784--87
This standard was proposed by the Ministry of Electronics Industry and is under the jurisdiction of the Standardization Research Institute of the Ministry of Electronics Industry. This standard was drafted by Zhenjiang Cable Plant. The main authors of this standard are Fan Meilin, Cheng Banghua and Pan Yunkun.
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