The LPS-151/152 is a DC Tracking Power Supply designed to provide three regulated voltage sources, covering ranges of 0 to 6V, 0 to 25V, and 0 to -25V. Both models are equipped with a built-in voltmeter and ammeter, allowing individual monitoring of output conditions for each section of the supply.
Function Description:
The power supply offers three distinct voltage sources: a +6V range source and two ±25V range sources. The ±25V sources can operate in a voltage tracking mode, providing flexibility for various applications. In the fixed tracking mode, the -25V source tracks the +25V source with a 1:1 ratio. Alternatively, in the variable tracking ratio mode, the -25V source tracks the +25V source by an adjustable ratio ranging from 50% to 100%. A unique feature is the ability to obtain a 50V source by connecting the load across the +25V and -25V terminals, though in this configuration, the 6V output cannot be used. Voltage and current settings are controlled via front panel controls and are monitored by the integrated voltmeter and ammeter.
Important Technical Specifications:
- Output Voltage Ranges:
- 0 to 6Vdc
- 0 to 25Vdc
- 0 to -25Vdc
- Output Current Ranges:
- LPS-151: 0 to 3A (6V), 0 to 0.5A (±25V)
- LPS-152: 0 to 5A (6V), 0 to 1A (±25V)
- Ripple: Less than 3mV, p-p
- Line Regulation (output stability): Less than 3mV plus 0.01% of the input change for a 10% change of line voltage.
- Load Regulation: Less than 3mV plus 0.01% of the load value from no load to full load.
- Tracking Voltage: In ratio tracking mode, the -25V source tracks the +25V source by an adjustable ratio of 50% to 100%.
- Voltmeter: Dual scale (0 to 7 volts and 0 to 30 volts). Meter range and polarity are selected by the METER switch.
- Voltmeter Accuracy: 5% of the full scale reading.
- Ammeter: Dual scale.
- LPS-151: 0 to 0.6 amperes and 0 to 3.5 amperes.
- LPS-152: 0 to 1.2 amperes and 0 to 6 amperes.
- Meter range and polarity are selected by the METER switch.
- Insulation Voltage: 1500 Vac applied for one minute between one of the AC input terminals and the case.
- Circuit Protection: Overload protection circuit with automatic resetting by sensing a constant current.
- Power Consumption:
- LPS-151: approx. 120VA
- LPS-152: approx. 220VA
- Heat Sink Temperature Range: At room temperature (23 to 25°C), 85°C (185°F) with 100% load.
- Operating Temperature Range: 0° to 35°C (32° to 95°F)
- Operating Humidity Range: 30 to 85% (non-condensing)
- Storage Temperature Range: -20 to +70°C (-4 to 158°F)
- Size (W x H x D):
- LPS-151: 8½ x 5¼ x 13 in. (215 x 132 x 332 mm)
- LPS-152: 8½ x 5¼ x 14⅛ in. (215 x 132 x 360 mm)
- Weight:
- LPS-151: 13½ lbs. (6.1 kg)
- LPS-152: 15½ lbs. (7.5 kg)
- Supplied Accessories: Instruction Manual
Usage Features:
The front panel includes a POWER switch (1) with an associated pilot lamp (2) to indicate power status. METER selector switches (3, 4, 5) assign the voltmeter and ammeter to specific ranges (+25V, -25V, or +6V sources). The REFERENCE/±25V control (6) sets the output voltage level for the ±25V range sources. A TRACKING RATIO selector switch (7) allows selection between fixed and variable tracking modes for the -25V source. The TRACKING RATIO control (9) adjusts the tracking ratio in variable mode. Case ground terminal (8) connects directly to the case.
Output terminals include COM (10, 16), +25V Source (11), -25V Source (13), and 6V Source (15). Current controls (12, 14, 17) set the output current limits for the respective sources. The VOLTAGE +6V control (18) sets the output voltage for the +6V source. The voltmeter (19) and ammeter (23) provide visual indications of voltage and current.
Rear panel features include the AC Cord (24), Fuse (25) (LPS-151: 2A slow blow for 120V, 1A slow blow for 240V; LPS-152: 3A slow blow for 120V, 1.5A slow blow for 240V), and a Heat sink (26) for heat dissipation.
Operating Precautions:
- Input Power: Line voltage should be within ±10% of rated voltage (100V, 120V, 200V, or 234V). Units shipped in the U.S. are set for 120Vac, with a permissible operating range of 108 to 132 Vac. For other voltages, transformer tap connections must be changed (refer to Section 7.5).
- Output Terminals: Connecting COM terminal (10) or (16) to case ground terminal (8) grounds both COM terminals. When obtaining 25-50V output across +25V and -25V terminals, ensure both COM terminals are ungrounded. Use lead wires of sufficient rating for the current drawn.
- General: Avoid operating the power supply under conditions that cause red zone readings on the meters. Always remove the AC line cord from the power source before replacing the fuse. Long lead wires can induce currents and cause oscillation; use an appropriately valued electrolytic capacitor at the load to maintain stability.
- Environmental Considerations: Avoid dusty environments, high humidity, poor ventilation, proximity to other power sources, or direct sunlight. The ambient operating temperature should be between 0° to 35°C. Ensure adequate ventilation, especially around the heat sink.
Maintenance Features (Calibration Procedures):
The manual provides detailed calibration procedures for the meters and voltage outputs, as well as instructions for changing transformer tap connections for different AC line voltages.
- Preparation:
- Meter Mechanical Zero Adjustment: With the power supply off and capacitors discharged, adjust the zero adjust screws (20, 22) on both the voltmeter and ammeter until the pointers indicate exactly zero. Rotate the screws slightly in the opposite direction after setting zero to relieve movement tension.
- Initial Control Settings: Set VOLTAGE +6V (18), CURRENT controls (12, 14, 17), and REFERENCE ±25V (6) to full counterclockwise. Set TRACKING RATIO selector (7) to FIXED and REFERENCE +25 METER selector (3) to pushed in.
- Meter Zero Adjustment with Power On:
- +25V Range: Turn power on, push REFERENCE +25V METER selector (3), and adjust VR502 (0 ADJ) on circuit board T-2665A until the voltmeter reads zero.
- -25V Range: Push TRACKING -25V METER selector (4), and adjust VR504 (0 ADJ) on T-2665A until the voltmeter reads zero.
- +6V Range: Push +6V METER selector (5), and adjust VR506 (0 ADJ) on T-2665A until the voltmeter reads zero.
- Voltmeter Adjustment with Power On:
- +25V Range: Push REFERENCE +25V METER selector (3). Connect a calibrated voltmeter across +25V output (+) and COM (-) terminals. Set REFERENCE/±25V control to read 25.0Vdc on the calibrated voltmeter. Adjust VR501 (VOLTS) on T-2665A until the power supply voltmeter indicates 25V.
- -25V Range: Push TRACKING -25V METER selector (4). Connect a calibrated voltmeter across -25V output (+) and COM (-) terminals. Confirm both voltmeters indicate -25V.
- +6V Range: Push +6V METER selector (5). Connect a calibrated voltmeter across +6V (+) and COM (-) terminals. Use +6V voltage control to make the calibrated voltmeter indicate 6.0Vdc. The power supply voltmeter should also indicate 6 volts.
- Ammeter Adjustments:
- +0.5A Range (LPS-151) / +1A Range (LPS-152): Push REFERENCE +25V METER selector. Set +0.5A (or +1A for LPS-152) CURRENT control fully clockwise. Connect a calibrated ammeter and a 12.5W (or 25W for LPS-152) rheostat as shown in Figure 7-1. Set REFERENCE/±25V control to 25V. Adjust the rheostat until the calibrated ammeter indicates 0.5A (or 1.0A). Adjust VR503 (FULL SCALE) on T-2665A for the power supply ammeter to read 0.5A (or 1.0A).
- -25V Range: Similar procedure as above, but push TRACKING -25V METER selector, set -0.5A (or -1A) CURRENT control fully clockwise, set REFERENCE/±25V control to -25V, and adjust VR505 (FULL SCALE) on T-2665A.
- 3A Range (LPS-151) / 5A Range (LPS-152): Push +6V METER selector. Connect a calibrated ammeter and an 18W (or 30W for LPS-152) rheostat as shown in Figure 7-3. Set 3A (or 5A) CURRENT control fully clockwise. Set REFERENCE/±25V control to +6V. Adjust the rheostat until the calibrated ammeter indicates 3.0A (or 5.0A). Adjust VR507 (FULL SCALE) on T-2665A for the power supply ammeter to read 3A (or 5A).
- Connections for Other AC Line Voltages: Instructions are provided for changing transformer tap connections to adapt the unit for 100V, 120V, 200V, 220V, and 240V nominal line voltages, along with corresponding fuse ratings.
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