CS-03 Part I — Requirements for Terminal Equipment (TE) and Related Access Arrangements Intended for Direct Connection to Analog Wireline Facilities (sf09836)

2.3.6 Ringdown Voice Band Private Line and Voice Band Metallic Channel Interface

During normal operation, TE intended for connection to ringdown voice band private line interfaces or voice band metallic channel interfaces shall ensure that:

1. Ringing voltage does not exceed the voltage and current limits specified in Section 2.3.9.4, and is:
   1. applied to the ring conductor with the tip conductor grounded for 2-wire interfaces; or
   2. simplexed on the tip and ring conductors with ground simplexed on the tip_1 and ring_1 conductors for 4-wire interfaces.
2. Except during the signalling mode or for monitoring voltage, there is no significant positive DC voltage (not over + 5 V) with respect to ground:
   1. for 2-wire ports between the tip lead and ground and the ring lead and ground, and
   2. for 4-wire ports between the tip lead and ground, the ring lead and ground, the tip_1 lead and ground, and the ring_1 lead and ground.
3. The DC current per lead under short circuit conditions shall not exceed 140 mA.

2.3.6.1 Method of Measurement

1. Inspect the appropriate circuit diagrams to verify the following:
   1. Ringing voltage is used for alerting only.
   2. Ringing voltage is applied to the ring lead with the tip lead grounded for 2-wire interfaces.
   3. Ringing voltage is simplexed on tip and ring leads, and ground is simplexed on T1 and R1 leads for 4-wire interfaces.
2. Perform the tests specified in Section 2.3.9 to verify compliance with the ringing source requirements in the signalling state.
3. Place the TE in the idle state.
4. Connect a DC voltmeter between tip lead and ground of the TE and measure the voltage. Record the polarity.
5. Repeat step (4) for the ring lead.
6. Repeat step (4) for T1 and R1 leads of the TE if testing a 4-wire interface.
7. Repeat steps (4) to (6) with the TE in talk state.
8. Place the TE in idle state.
9. Connect a current metre between the tip and ring leads and measure the short circuit current.
10. Repeat step (9)  between tip lead and ground and between ring lead and ground.
11. Repeat step (9) for T1 and R1 leads if testing a 4-wire interface.
12. Repeat steps (9) to (11) for talk state.

2.3.7 Connection of Non‑registered Equipment to Registered TE or Protective Circuitry

2.3.7.1 Conducting Paths to Telephone Connections, Auxiliary Leads and E&M Leads

Leads or any elements having a conducting path to telephone connections, auxiliary leads or E&M leads shall:

1. be reasonably physically separated and restrained from, and be neither routed in the same cable as, nor use the same connector as leads or metallic paths that connect power connections.
2. be reasonably physically separated and restrained from, and be neither routed in the same cable as, nor use adjacent pins on the same connector as metallic paths to lead to non-registered equipment, when specification details do not illustrate that interface voltages are less than the non-hazardous voltage source limits outlined in Section 2.3.8.

2.3.7.2 Method of Measurement

1. Inspect the schematic diagram and identify leads for connecting to the network interface, including telephone connections, auxiliary leads and E&M leads. Also identify power leads to non-registered TE.

2. Identify leads to non-registered TE with hazardous voltages.
3. Inspect equipment to verify that leads for connection to the network are adequately separated from power leads and from leads to non-registered TE with hazardous voltages.
4. Verify that leads for connection to the network are not routed in the same cable and do not use the same connector as power leads or leads to non-registered TE with hazardous voltages.
5. If leads for connection to the telephone network are in the same connector as leads to non-registered TE with hazardous voltages, verify that they are not on adjacent pins.

2.3.8 Non-hazardous Voltage Source

A voltage source is considered to be non-hazardous if it complies with the requirements of Section 2.2 and either Section 2.4 or 2.5 of this document, with all connections to the source, other than primary power connections, treated as "telephone connections", and if such source supplies voltages that do not exceed the following under all modes of operation and of failure:

1. AC voltages less than 42.4 V peak;
2. DC voltages less than 60 V; and
3. combined AC and DC voltages less than 42.4 V peak when the absolute value of the DC component is less than 21.2 V, and less than (32.8 + 0.454 x Vdc) when the absolute value of the DC component is between 21.2 and 60 V.

2.3.9 Ringing Source Limitations

Ringing sources for all classes of OPS interfaces shall meet the following requirements:

2.3.9.1 Ringing Signal Frequency

The ringing signal shall only use frequencies for which the fundamental component is equal to or less than 70 Hz.

2.3.9.2 Ringing Signal Voltage

The ringing voltage shall be less than 300 V peak-to-peak and less than 200 V peak-to-ground across a resistive termination of at least 1 Mega-ohm (M Ω).

2.3.9.3 Ringing Signal Interruption Rate

The ringing voltage shall be interrupted to create quiet intervals of at least one second (continuous) duration, each separated by no more than five seconds. During quiet intervals, the voltage to ground shall not exceed the voltage limits specified in paragraph (1) of Section 2.3.4.

2.3.9.4 Ringing Signal Sources

Ringing voltage sources shall comply with the following requirements:

1. If the ringing current through a 500 ohm (Ω) (and greater) resistor does not exceed 100 mA peak-to-peak, a ring trip device or a monitoring voltage are not required.
2. If the ringing current through a 1500 Ω (and greater) resistor exceeds 100 mA peak-to-peak, the ringing source shall include a current-sensitive ring trip device in series with the ring lead that will trip ringing as described in Figure 2.3.9.4 and Table 2.3.9.4, in accordance with the following conditions:
   1. If the ring trip device operates as outlined in Figure 2.3.9.4 and Table 2.3.9.4 with R = 500 Ω (and greater), monitoring voltage is not required.
   2. If, however, the ring trip device only operates as outlined in Figure 2.3.9.4 and Table 2.3.9.4 with R = 1500 Ω (and greater), then the ringing voltage source shall also provide a monitoring voltage between -19 Vdc and -56.5 Vdc, with respect to ground, on the tip or ring conductor.
3. If the ringing current through a 500 Ω (and greater) resistor exceeds 100 mA (peak-to-peak) but does not exceed 100 mA peak-to-peak with 1500 Ω (and greater) termination, the ringing voltage source shall include either a ring trip device that meets the operating characteristics specified in Figure 2.3.9.4 and Table 2.3.9.4 with 500 Ω (and greater), or a monitoring voltage as described in (b) above.

Figure 2.3.9.4 — Ringing Protection

2.3.9.5 Method of Measurement

1. Connect the frequency counter to the tip and ring leads of the TE and measure the frequency of the ringing voltage.
2. If the TE is a 4-wire device, connect the frequency counter to the tip and ring leads of the TE tied together, and to the T1 and R1 leads of the TE, and measure the frequency of the ringing voltage.
3. Connect the TE to the test circuit of Figure 2.3.9.5(a) if the TE is a 2-wire device or to the test circuit of Figure 2.3.9.5(b) if the TE is a 4-wire device.

4. Set switch S1 to "a" and measure:
   1. peak-to-peak ringing voltage;
   2. peak-to-ground ringing voltage;
   3. ringing time interval;
   4. non-ringing time interval.
5. Set switch S1 to position "b" and initiate ringing.
6. Measure and record the peak-to-peak voltage.
7. If ringing is tripped, measure the duration of applied ringing.
8. Convert the voltage recorded in step (6) to peak-to-peak current in mA.
9. Set switch S1 to position "c" and repeat steps (5) to (8).
10. Refer to Table 2.3.9.4 to determine compliance with ringing voltage and the need for a tripping device and a monitoring voltage.

11. If a monitoring voltage is required, connect the oscilloscope (DC coupled), using the 10x probe, to measure the DC voltage present during the ringing and non-ringing states.

Figure 2.3.9.5(a) — Ringing Sources, 2-Wire

Notes:

1. A 10x probe is normally used to obtain the reading. The input impedance of the probe should be equal to or greater than 1 M Ω.
2. When the TE makes provision for an external connection to ground (G), the TE shall be connected to ground. When the TE makes no provision for an external ground, the TE shall be placed on a ground plane which is connected to ground and has overall dimensions at least 50% greater than the corresponding dimensions of the TE. The TE shall be centrally located on the ground plane without any additional connection to ground. At no point in time should any metal surface of the TE come in contact with the ground plane. If the TE has exposed metal that could come in contact with the metal ground plane, a thin insulating material shall be inserted between the ground plane and the TE.

Figure 2.3.9.5(b) — Ringing Sources, 4-Wire

Notes:

1. A 10x probe is normally used to obtain the reading. The input impedance of the probe should be equal to or greater than 1 M Ω.
2. When the TE makes provision for an external connection to ground (G), the TE shall be connected to ground. When the TE makes no provision for an external ground, the TE shall be placed on a ground plane which is connected to ground and has overall dimensions at least 50% greater than the corresponding dimensions of the TE. The TE shall be centrally located on the ground plane without any additional connection to ground. At no point in time should any metal surface of the TE come in contact with the ground plane. If the TE has exposed metal that could come in contact with the metal ground plane, a thin insulating material shall be inserted between the ground plane and the TE.

2.3.10 Hazards Due to Intentional Paths to Ground

2.3.10.1 Connections with Operational Paths to Ground

TE with an intentional DC conducting path to earth ground at operational voltages that was excluded during the dielectric strength test of Section 2.2 shall have a DC current source derived from a low voltage current source not exceeding 12 V, applied between the following points:

1. Telephone connections, including tip, ring, tip_1, ring_1, E&M leads and auxiliary leads; and
2. Earth grounding connections.

For each test point, gradually increase the current from zero to 1A, and maintain the current for one minute. The voltage between (1) and (2) shall not exceed 0.1 V at any time.

2.3.10.1.1 Method of Measurement

1. Connect the TE to the test circuit of Figure 2.3.10.1.1.
2. Connect the current source between the intentionally grounded telephone connection and the earth grounding connection.
3. Gradually increase the current from 0 A to 1 A and maintain this current for one minute.
4. Monitor and record the voltage drop across the connections under test. Verify that the voltage does not exceed 0.1 V at any time.
5. Repeat steps (2) to (4) for each applicable connection.

Figure 2.3.10.1.1 — Intentional Operational Paths to Ground

2.3.10.2 Connections With Protection Paths to Ground

TE with an intentional DC conducting path to earth ground for protection at the leakage current test voltage that was removed during the longitudinal steady state voltage test of Section 2.2.1 shall have a 60 Hz voltage source applied between the following points:

1. Simplexed telephone connections, including tip and ring, tip_1 and ring_1, E&M leads and auxiliary leads; and
2. Earth grounding connections.

Gradually increase the voltage from zero to 120 Vrms for TE, or 300 Vrms for protective circuitry, and maintain the voltage for one minute. The current between (1) and (2) shall not exceed 10 mA peak at any time.

As an alternative to carrying out this test on the complete equipment or device, the test may performed separately on components, sub-assemblies and simulated circuits outside the unit, provided the test results would be representative of the results of testing the complete unit.

2.3.10.2.1 Method of Measurement

1. Connect the TE to the test circuit of Figure 2.3.10.2.1.
2. Connect the voltage source between the telephone connection (1) and the earth grounding connection (2).
3. Gradually increase the voltage from zero to the specified level (120 Vrms for TE and 300 Vrms for protective circuit) and maintain this voltage for one minute.
4. Monitor and record the current between (1) and (2). Verify that the current does not exceed 10 mA peak at any time.
5. Repeat steps (2) to (4) for each applicable connection.

Figure 2.3.10.2.1 — Intentional Protective Paths to Ground

2.4 Surge Voltage

For both Telephone Line Surge Type A and Telephone Line Surge Type B, surges shall be applied asfollows:

1. With the equipment in states that may affect compliance with the requirements of this specification. If an equipment state cannot be achieved by normal means of power, it may be achieved artificially by appropriate means.
2. With equipment leads not being surged (including telephone connections, auxiliary leads and terminals for connection to non-registered equipment), terminated in a manner which occurs in normal use.
3. Under reasonably foreseeable disconnection of primary power sources, with primary power cords plugged and unplugged, if so configured.

2.4.1 Telephone Line Surge — Type A

2.4.1.1 Metallic Voltage Surge

Apply two metallic voltage surges (one of each polarity) to equipment between any pair of connections on which lightning surges may occur; this includes:

1. tip to ring
2. tip_1 to ring_1, and
3. for a 4-wire connection which uses simplexed pairs for signalling, tip to ring_1 and ring to tip_1.

The surge shall have an open circuit voltage waveshape in accordance with Figure 2.4.1.2(a) and a short circuit current waveshape in accordance with Figure 2.4.1.2(b).

The rise time (T_r) and the decay time (T_d) values for these conditions, as well as the peak voltage and the peak short circuit current values, shall be in accordance with Table 2.4.1.1.

2.4.1.2 Method of Measurement (Tip to Ring)

Configure the surge generator as outlined in Section 2.4.1.1. Connect the equipment to be surged to the generator terminals (see Figure 2.4.2.2(a)).

1. Set switch S3 to position "b". Energize and fire the surge generator.
2. Check the TE operation and record the results.
3. Reverse the polarity of the surge and repeat steps (1) and (2).
4. Set switch S1 to position "b". Repeat steps (1) to (3) for all equipment operating states.
5. Return all switches to position "a".

Figure 2.4.1.2(a) — Open Circuit Voltage Waveshape, T_r x T_d

Figure 2.4.1.2(b) — Open Circuit Current Waveshape, T_r x T_d

2.4.1.3 Longitudinal Voltage Surge

Apply two longitudinal voltage surges (one of each polarity) to equipment from any pair of connections on which lightning surges may occur, including the tip and ring pair and the tip_1 and ring_1 pair, to each of the following:

1. Earth grounding connections; and
2. All leads intended for connection to non‑registered equipment, connected together.

The surge shall have an open circuit voltage waveshape in accordance with Figure 2.4.1.2(a) and a short circuit current waveshape in accordance with Figure 2.4.1.2(b). The rise time (T_r) and the decay time (T_d) values for these conditions, as well as the peak voltage and the peak short circuit current values, shall be in accordance with Table 2.4.1.3.

2.4.1.4 Method of Measurement (Tip and Ring together/and to Ground)

Configure the surge generator as outlined in Section 2.4.1.3. Connect the equipment to be surged to the generator terminals (see Figure 2.4.2.2(a)).

1. Set switch S3 to position "c" and switch S4 to position "b". Energize and fire the surge generator.
2. Check the TE operation and record the results.
3. Reverse the polarity of the surge and repeat steps (1) and (2).
4. Set switch S1 to position "b". Repeat steps (1) to (3) for all equipment operating states.
5. Return all switches to position "a".

2.4.1.5 Method of Measurement (Tip and Ring Together/and to Other Leads)

Configure the surge generator as outlined in Section 2.4.1.3. Connect the equipment to be surged to the generator terminals. See Figure 2.4.2.2(a).

1. Set switch S3 to position "d" and switch S4 to position "b". Energize and fire the surge generator.
2. Check the TE operation and record the results.
3. Reverse the polarity of the surge and repeat steps (1) and (2).
4. Set switch S1 to position "b". Repeat steps (1) to (3) for all equipment operating states.
5. Return all switches to position "a".

2.4.1.6 Failure Modes Resulting From the Application of Type A Telephone Line Surges

TE and network protection devices shall be evaluated to determine if they can achieve an off-hook state after application of metallic and longitudinal surges. An off-hook condition is achieved by the ability to draw 16 mA or greater from a loop simulator circuit. If an off-hook state cannot be achieved, signal power, billing, and hearing aid compatibility tests need not be conducted.

Regardless of operating state, equipment and circuitry can be in violation of the transverse balance requirements of Section 3.6 and for limited distance modems TE, the longitudinal signal power requirements of Part VII Section 3.1.1 (3), provided that:

1. Such failure results from an intentional, designed failure mode which has the effect of connecting telephone or auxiliary connections with earth grounds; and
2. If such a failure-mode state is reached, the equipment is designed so that it would become substantially and noticeably unusable by the user, or an indication is given (e.g. an alarm) in order for such equipment to be immediately disconnected or repaired.

2.4.2 Type B Telephone Line Surge

2.4.2.1 Metallic Voltage Surge

Apply two metallic voltage surges (one of each polarity) to equipment between any pair of connections on which lightning surges may occur, including: (1) tip to ring; (2) tip_1 to ring_1; and (3) for a 4-wire connection that uses simplexed pairs of signalling, tip to ring_1 and ring to tip_1.

The surge shall have an open circuit voltage waveshape in accordance with Figure 2.4.1.2(a) and a short circuit current waveshape in accordance with Figure 2.4.1.2(b). The waveshapes are based on the use of ideal components in Figure 2.4.2.2(b) with S2 in position "M". The rise time (T_r) and the decay time (T_d) values for these conditions, as well as the peak voltage and the peak short circuit current values, shall be in accordance with Table 2.4.2.1.

2.4.2.2 Method of Measurement (Tip to Ring)

Configure the surge generator as outlined in Section 2.4.2.1. Connect the equipment to be surged to the generator terminals. See Figure 2.4.2.2(a).

1. Set switch S3 to position "b". Energize and fire the surge generator.
2. Check the TE operation and record the results.
3. Reverse the polarity of the surge and repeat steps (1) and (2).
4. Set switch S1 to position "b". Repeat steps (1) to (3) for all equipment operating states.
5. Return all switches to position "a".

Figure 2.4.2.2(a) — Surge Voltage Application

Note: When the TE makes provision for an external connection to ground (G), the TE shall be connected to ground. When the TE makes no provision for an external ground, the TE shall be placed on a ground plane that is connected to ground and has overall dimensions at least 50% greater than the corresponding dimensions of the TE. The TE shall be centrally located on the ground plane without any additional connection to ground. At no point in time should any metal surface of the TE come in contact with the ground plane. If the TE has exposed metal that could come in contact with the metal ground plane, a thin insulating material shall be inserted between the ground plane and the TE.

Figure 2.4.2.2(b) — Simplified Surge Generator

Note: 

When the TE makes provision for an external connection to ground (G), the TE shall be connected to ground. When the TE makes no provision for an external ground, the TE shall be placed on a ground plane that is connected to ground and has overall dimensions at least 50% greater than the corresponding dimensions of the TE. The TE shall be centrally located on the ground plane without any additional connection to ground. At no point in time should any metal surface of the TE come in contact with the ground plane. If the TE has exposed metal that could come in contact with the metal ground plane, a thin insulating material shall be inserted between the ground plane and the TE.

2.4.2.3 Longitudinal Voltage Surge

Apply two longitudinal voltage surges (one of each polarity) to equipment from any pair of connections on which lightning surges may occur, including the tip and ring pair and the tip_1 and ring_1 pair, to each of the following:

1. Earth grounding connections, and
2. All leads intended for connection to non-registered equipment, connected together.

For each output lead of the surge generator, with the other lead open, the surge shall have an open circuit voltage waveshape in accordance with Figure 2.4.1.2(a) and a short circuit current waveshape in accordance with Figure 2.4.1.2(b). The waveshapes are based on the use of ideal components in Figure 2.4.2.2(b) with S2 in position "L". The rise time (T_r) and the decay time (T_d) values for these conditions, as well as the peak voltage and the peak short circuit current values, shall be in accordance with Table 2.4.2.3.

2.4.2.4 Method of Measurement (Tip and Ring together/and to Ground)

Configure the surge generator as outlined in Section 2.4.2.3. Connect the equipment to be surged to the generator terminals. See Figure 2.4.2.2(a).

1. Set switch S3 to position "c" and switch S4 to position "b". Energize and fire the surge generator.
2. Check the TE operation and record the results.
3. Reverse the polarity of the surge and repeat steps (1) and (2).
4. Set switch S1 to position "b". Repeat steps (1) to (3) for all equipment operating states.
5. Return all switches to position "a".

2.4.2.5 Method of Measurement (Tip and Ring together/and to other Leads)

Configure the surge generator as outlined in Section 2.4.2.3. Connect the equipment to be surged to the generator terminals. See Figure 2.4.2.2(a).

1. Set switch S3 to position "d" and switch S4 to position "b". Energize and fire the surge generator.
2. Check the TE operation and record the results.
3. Reverse the polarity of the surge and repeat steps (1) and (2).
4. Set switch S1 to position "b". Repeat steps (1) to (3) for all equipment operating states.
5. Return all switches to position "a".

2.4.2.6 Failure Modes Resulting From the Application of Type B Telephone Line Surges

Registered TE and registered protective circuitry shall withstand the energy of surge type B without causing permanent opening or shorting of the interface circuit and without sustaining damage that will affect compliance with this specification.

2.5 Power Line Surge

2.5.1 Requirements

Apply six power line surges (three of each polarity) to equipment between the phase and neutral terminals of the AC power line while the equipment is being powered. The surge shall have an open circuit voltage waveshape in accordance with Figure 2.4.1.2(a), and a short circuit current waveshape in accordance with Figure 2.4.1.2(b). The rise time (T_r) and the decay time (T_d) values for these conditions, as well as the peak voltage and the peak short circuit current values, shall be in accordance with Table 2.5.1.

Surges are applied:

1. with the equipment in all states that can affect compliance with the requirements of this specification. If an equipment state cannot be achieved by normal means of power, it may be achieved artificially by appropriate means.
2. with equipment leads not being surged (including telephone connections, auxiliary leads and terminals for connection to non‑registered equipment), terminated in a manner that occurs in normal use.

2.5.2 Method of Measurement

Using the power line decoupler in series with the equipment, configure the generator as outlined in Figure 2.4.2.2(a).

1. Set switches S3 and S4 to position "a".
2. Set switch S2 to position "b". Energize and fire the surge generator.
3. Check TE operation and record the results.
4. Set switch S1 to position "b". Reverse the polarity of the surge and repeat steps (1) and (2).
5. Repeat steps (1) to (4) for all equipment operating states.
6. Return all switches to position "a".