1-ODOT_106_Group5_PDC_252_isolator.pdf

DATA SHEET :ACI-88-252

P.O. Box 10450 Zephyr Cove, NV. 89448 • PH (925) 461-0881 • FAX (925) 461-0884

Model 252 AC Isolator:

Description:

The PDC Model ACI-88 dual channel AC isolator is designed specifically to meet the California Department of Transportation, Model 252 specifications. Each channel of the Model 252 shall present a true signal (ground closure) at the output of its optical coupling device when a AC signal of +80 +-5 VAC is applied to its receptive input for a period of 100 milliseconds. Each channel is provided with switches, which will invert the output signals. When the switch for a channel is set to invert, the respective channel will maintain a true output (ground closure) until a voltage of +80 +-5 VAC is applied for a minimum of 100 milliseconds at which time the respective output will go false. A transition from false to true will occur when the respective input voltage drops to 70 volts for 100 milliseconds.

All electronics are provided on a single sided P.C. board with an aluminum front panel. The P.C. board is provided with a solder mask, silk screen identifying all component locations and is conformally coated to resist adverse environmental conditions.

Installation:

The Model 252 AC Isolator intermates with the appropriate traffic signal control or traffic management system cabinet input file.

Connector pinouts are shown in Fig. 1. The connector mates with a Cinch #250-22-30-xxx or equivalent.

Pin Function Pin Function A DC ground N AC+

B +24 VDC P NA

C NA R NA

D Input #1 S NA E Input #1 common T NA F Output #1 (C) U NA H Output #1 (E) V NA J Input #2 W Output #2 (C) K Input #2 common X Output #2 (E) L Equipment ground Y NA

M AC- Z NA

FIG 1.

General Characteristics: Model ACI-88-252

Input: Voltage 135 VAC True State 80 +/-3 VAC, 100 msec.

False State 70 +/-3 VAC, 100 msec.

Output: Voltage 30 VDC max.(open collector) Current 50 mamp sink(true state) Power: Voltage +24 VDC Current 100 mamp max.

Isolation: Voltage 2500 VAC Resistance 1000 megohm.

Transient suppression: Energy 50 Joules Mechanical: Length 7.00 IN.

Width 1.12 IN.

Height 4.50 IN.

Weight 0.35 LBS

Alignment procedure: There is no alignment procedure required for the operation of the AC Isolator.

Adjustments: Input Voltage level pots are factory set for 80 and 70 volts.

Theory of Operations:

General:

The AC Voltage is applied to the input circuit, consisting of a transient suppresser, full wave bridge, and resistive voltage divider. Refer to Fig. 2. The input circuit resistive divider presents a full wave rectified signal to the diode primary of the optical couplers. The resistive dividers are calculated such that the threshold of the optical coupler is reached when the input voltage is approximately 70 and 80 volts respectively. If the input voltage exceeds 80 VAC the secondary of the optical coupler will trigger the 100 Msec. timer. Assuming the input remains the 100 Msec.

timer will time out and set the valid input signal latch. The latch in turn drives the output opticalcoupler turning on the output transistor. If the input voltage falls below 70 VAC the secondary input optical coupler turns off triggering a 100 Msec. timer. If this condition exists for 100 Msec. the valid input signal latch reset turning off the output transistor. Any time the input voltage exceeds the threshold of the input optical coupler during this period the 100 Msec. timer will be reset.

Detailed Circuit Description:

Refer to circuit schematic, Fig. 3. Power and a DC reference for all circuits is derived from the combination of R17 and CR3 driven by the external 24 VDC power supply. Let’s consider channel 1 only, with AC input on pins D & E and output on pins H & F. Assume A voltage greater than 80 VAC is applied to the input. This voltage is rectified by CR1 and applied to resistor string R2, R3, R4 and R5. R3 has been set so that at 80 VAC the diode of the input coupler U1 will be saturated, creating a low signal at the collector of the output transistor (U1). This low signal will discharge capacitor C1 and produce a low signal at U5-2. R5 has been set so that at 70 VAC the diode of the input coupler U2 will be saturated, creating a low signal at the collector of the output transistor (U2). The low signal U5-2 will then create a high transition at output U2-3. Triggering the 100 Msec. one shot (U6-4). After the one shot (U6) times out latch (U8) will be clocked and will lock in an output signal to Q1 which will cause a true output on channel

1. When the input voltage goes below 70 VAC the output collector of U2 will remain high. This high will appear on U5-12,13 causing U5-11 to go low. Triggering the 100 Mesc. (U6-11). If the input stays below 70 VAC in excess of 100 Msec. U6 will time out resetting latch U8and causing the output from channel 1 to go false.

Channel 2 may be analyzed in an identical manner to channel 1.

Maintenance:

Preventive maintenance: The AC isolator may be stored in any non-corrosive environment until needed. Once installed and operating the isolator needs no preventive maintenance during normal operation.

Troubleshooting:

Should improper operation of the Isolation module be observed, the technician should first become thoroughly familiar with the theory of operation before attempting to troubleshoot. Refer to isolation schematic, Fig 3 and Fig 4 for component location. Proceed with the following paragraphs to isolate the component problem.

Trouble shooting sequence chart:

Problem Solution A) No Output Verify input voltage <85 VAC

Verify +24 VDC pin B input file Go to trouble shooting problem 1.

B) False Outputs Verify input voltage <85 VAC Check 12 VDC CR3 Cathode Check 100 Msec timers U6, U7

C) Output Always On Verify input voltage >65 VAC Go to problem 2.

Prelimenary checks and voltage measurements:

1. Check for cabinet +24 VDC at pin B, ground at pin A.

2. Check AC inputs at pins D,E,J, and K. Check for proper voltage levels.

3. Check output connections and proper loading.

If the preliminary checks 1 thru 4 are normal, then the problem must be within the AC Isolation Module. Select problems 1 or 2 depending on the fault condition present. The isolation proceedures shown assume channel 1 of the module to be faulty.

Problem 1.

With >80 VAC applied, the output does not go true ( Saturated NPN transistor, pins H and F).

1. Verify that >80 VAC is applied to channel 1 input, pins D and E. Does indicator I1 illuminate? If no go to 2A. If yes replace Q2. If this does not correct the problem then replace optical isolation U9.

2A. Depress test switch S1. Does I1 illuminate? If yes go to 3.

B. Short collector Q1 to ground. Does I1 illuminate? If yes go to 3.

C. Short across anode and cathode of I1. Does output go true? If yes replace I1. If no replace Q2. If this does not correct the problem then replace optical isolator U9.

3. Check state of U8-1. If low go to 4A. If high (11-12 VDC) , check continuity from U8-1 to base of Q1.

4A. Check state of U8-2. If high proceed to 4B.If high proceed to 4B. If low replace U8 note that the problem could also be a shorted input at U5.

B. Check state of U8-4. If high go to 11. If low proceed to 5A.

5A. Check signal at U1-1. If signal is as inFig. 5A, the proceed to 6A.

B. If signal is half wave recified replace diode bridge CR1.

C. If no signal is present at U1-1, then measure signal at + terminal of CR1. If no signal at this point, replace CR1.

If full wave rectified signal at this point,replace U1. Check continuity to U1-1.

6A. Check signal at U1-5. If signal is as in Fig. 5C, then proceed to 7A.

B. If the signal is 12 VDC then replace U1.

C. If the signal is 0 VDC remove one leg of C1. If signal becomes a square wave replace C1. If not replace U2.

7A. Check signal at U2-5. If signal is as in Fig. 5B then proceed to 8.

B. If signal is 12 VDC replace U2.

C. If signal is 0 VDC replace U2.

8. Check U5-3. If high proceed to 9. If low replace U5.

9. Remove input voltage. If U5-3 goes low then proceed to 10. If not replace U5.

10. Observe U6-7. Re-apply >70 to channel 1 input. Signal shall go low for 100 Msec. and then high. If this occurs, replace U6, otherwise replace U5.

11. Check U5-11. Siganl should be a square wave. If yes replace U6. If no repace U5.

Problem 2.

Output goes true with greater than 80 VAC, however will not go false if input drops below 70 VAC.

1. With output true and input below 70 VAC does indicator I1 illuminate. If yes proceed to 2. If no replace Q2. If this does not not correct the problem then replace U9.

2. Check U8-1. If high proceed to 3. If low replace Q1.

3. Check U8-4. If low replace U6. If high replace U8.

ACI-88-252 PARTS LIST ASSY #00353

Item Qty PDC P/N Description MFG. MFG P/N Ref Des.

1 1 00353 PC Board Fab. PDC 00353 2 1 00118 Front Label PDC 00118 3 1 00134-1 Label PDC 00134-1 4 1 00333-2 Handle PDC 00333-2 5 2 H0012 Angle bracket G&C 6263 6 2 S0002 Switch C&K 7107SD9ABE S1,S2 7 2 LD0004 L.E.D. Monsanto MV5020 I1,I2 8 6 IC0001 Opto Isolator Motorola 4N25 U1,U2,U3, U4,U9,U10 9 1 IC0009 C-Mos 4013B Motorola MC14013B U8 10 1 IC0008 C-Mos 4093B Motorola MC14093B U5 11 2 IC0013 C-Mos 4098B Motorola MC14098B U6,U7 12 1 CR0005 Diode, Zener Fairchild 1N759 CR3 13 2 CR0004 Diode, Zener G.I. WL06M CR1,CR2 14 4 Q0004 Transistor G.E. 2N4401 Q1,Q2,Q3,Q4 15 2 VR0001 Varistor Panasonic 10DK241 VR1,VR2 16 4 R0066 Potentiomete Beckman EDN-KOAAOOB22 R3,R5,R20,R22 17 2 R0028 Res. 5 ohm 10W 10% Dale R1,R18 18 4 R0034 Res. 13K 2W 5% Dale R2,R4,R19,R21 19 1 R0025 Res. 680 ohm 1/2W 5% Dale R17 20 10 R0022 Res. 390K ohm 1/4W 5% Dale R6-9,R23-

26,R15,R32 21 4 R0024 Res. 3.3M ohm 1/4W 5% Dale R10,R11,R27,R28 22 2 R0020 Res. 150K ohm 1/4W 5% Dale R16,R33 23 2 R0007 Res. 1K ohm 1/2W 5% Dale R14,R31 24 2 R0014 Res. 12K ohm 1/4W 5% Dale R12,R29 25 2 R0016 Res. 27K ohm 1/4W 5% Dale R13,R30 26 2 S0004 Switch 4 position Grayhill 76SB04 S3 27 1 C0005 Cap. 22mf 35V Sprague C5 28 8 C0008 Cap. 0.1mf 50V 10% Sprague C1-3,C6-

8,C10,C11 29 2 C0013 Cap. 1000pf 500V 10% Thomson CSF C4,C9 30 2 Screw, PH PAN HD 4-40 x 5/16 31 2 Nut, Hex, Keps 4-40 32 2 Washer, split #4 33 2 Screw, self tapping #6