Regulated Power Supplies

Technical Specifications ANSI C34.2 Industrial Service Class is the most common requirement; other classes available.

Industrial Service Rating Class

• 15% continuous overload when operated at 40°C ambient temperature *
• 100% rated load current continuously at 50°C ambient temperature *
• 125% for two hours following continuous operation at 100% at 40°C ambient temperature
• 200% for 10 seconds following 100% operation at 40°C ambient temperature. (Altitude 3300 feet or lower)

Voltage Surge Protection
Two sets of surge suppressors are provided to protect against voltage surges from both the AC and DC sides as well as providing dv/dt protection.

Cooling
Convection or forced up-draft by means of sealed ball bearing motors protected by thermal-overload relays. Water cooling and liquid immersed cooling also available.

Transformer - Dry Type Class-H Insulated (150° C rise)
Nominally designed with two 2.5%, or one 5.0% taps above and below nominal input voltage. The transformer is of the separate primary and secondary type that withstands continuous operation 10% above rated input voltage at the maximum rated DC output. The coils are wound with continuous conductors (without splices or joints)

The coils are preheated, vacuum-varnished, impregnated and oven-baked for protection against dust, moisture and fumes.

The transformer core is constructed of high grade, grain-oriented silicon electrical steel of interleaved sheets operating at a flux density achieving efficiency levels of 98%.

Thermal-overload sensing devices are included in each leg of the transformer to detect winding over-temperature due to single phasing, overloading or loss of cooling air. They are to be used with the customer supplied trip device or with the optional incoming line circuit breaker trip device or magnetic starter. Activation de-energizes power to the unit.

Enclosure
The enclosure is a rigid, welded, free-standing, self-supporting, steel structure that is constructed of cold rolled, electro-zinc coated sheet steel. The base is fabricated from structural-steel members to carry the load of the electrical components.

The front and rear of the enclosure is serviceable through lockable, latch-type, full-length doors or panels.

The electro-zinc coated steel is covered with two coats of a suitable primer and two coats of ANSI 61 gray or a medium blue finish.

AC Input Voltages
Basic distribution AC input voltages are 230 and 460, three phase, 60 Hz. 208, 220, 240, 440, 480, 550, and 575 are also considered standard voltages.

Power supplies for other frequencies are available. These include 380 and 415 volts, three phase, 50 Hz.

High voltage classes of 2.4 kV, 5 kV, 6.9 kV, 8 kV and 15 kV are also standard. Higher voltage classes available up to 69 kV. (Switchgear optional; special auxiliary power is available.)

DC Output Voltages
125 and 250 volts DC are standard voltages used throughout the industry. Units with up to 1000 volts DC are also available.

Regulation (± 1 percent)
Voltage regulated supplies (±1 %) with rated load change and 10% AC input line change are standard. ±1%, current regulation is also available.

Ripple (Three-phase units)
5% rms at full output.

Efficiency
Normally better than 95% when operating near rated output.

Power Factor
Typically better than 90% when operating near rated output.

Variable Voltage and Current Output
Variable output by means of Silicon Controlled Rectifiers (SCRs) is standard.

Our solid-state controls, designed and manufactured by Rapid, offer instantaneous control of voltage from zero to full rating.

The basic power supply contains the main transformer, power on light, fuses and power semiconductors. Solid-state modules provide voltage regulation with current limit and are located in a sealed compartment. This is to protect modules against adverse atmospheric conditions.

Rapid SCR power supplies have multiple built-in protection systems and devices. In the event of a momentary output short circuit, Rapid's peak-current overload detector reduces the output to within design limits of the power supply. This eliminates unit shutoff due to momentary output short circuits. The detector continuously monitors the DC output for excessive current and will force the thyristors to phase back automatically when excessive current values are reached, thus reducing both voltage and current.

Current-limiting fuses are used for additional protection of the SCR. If there is a failure of a solid state protective module, the fuse will act as a backup system to protect the SCR's. Thermal detectors are built-in to protect the SCRs and transformer from excess temperatures.

Silicon Controlled Rectifier (SCR)
Diffused SCRs are selected to withstand transient voltages and surges without breakdown.

High-grade, hermetically sealed SCRs are mounted on heat sinks and protected with quick-acting silver sand fuses. PRV ratings of at least four times the rated voltage are used for additional transient voltage protection. The SCRs are pretested before they are installed into the power supply for their PRV ratings and leakage current.

In combining SCRs to obtain required output current, adequate provisions are made to insure that no SCR will carry current in excess of the safe operating current under any steady state or transient condition. SCRs are conservatively rated to provide ample capacity for overload. No matching is required.

SCR Heat Sink
The mating surfaces are coated with a heat conductive compound to improve the heat transfer of the rectifier device to the heat sink. This prevents formation of galvanic products or oxides between the surfaces. The heat sink is parallel to the direction of air flow with proper baffling provided to assure uniform distribution of air over its surfaces. The heat sink is located in the power supply for easy access to replace SCR and/or fuses. A heat sensing device is attached to the heat sink for the protection of the SCR from over temperature. This shuts the unit off when the unit is supplied with an AC magnetic starter or AC circuit breaker with undervoltage trip.

Unregulated Power Supplies Only

AC Input Voltages
Basic distribution AC input voltages are 230 and 460, three-phase, 60 Hz. 208, 220, 240, 440, 480, 550, and 575 are also considered standard voltages.

Power supplies for other frequencies are available. These include 380 and 415 volts, three-phase, 50 Hz.

High voltage classes of 2.4 kV, 5 kV, 6.9 kV, 8 kV and 15 kV are also standard. Higher voltage classes available up to 69 kV. (Switchgear optional; special auxiliary power is available.)

DC Output Voltages
The basic DC voltage used throughout the industry is 250 volts DC. Other voltages up to 1000 volts DC are also available.

125/250 volts* DC, three-wire is also available. The system consists of one three-phase, full-wave bridge at 250 volts DC 5% ripple; and a neutral wire from the main transformer to give 125 volts DC from neutral to either outside arm. The ripple will be slightly higher from the neutral to each arm.

125/250 volts* three-wire or four-wire with two series three-phase, full wave bridges are also available. A dual system of this type can be 100% unbalanced. It will have a 4.5% rms ripple content on both the 250 volt and 125 volt DC output terminals. This DC system can also be used for four-wire output consisting of two independent 125 volt DC outputs.

* Other dual output voltages are available.  

Voltage Regulation
6% typical with load change from 8% to 100% at constant AC input line voltage.

Ripple (Three-phase input)
4.5% rms (two-wire systems and three or four-wire systems double bridge only).

Efficiency
96% at 100% load at rated input voltage.

Power Factor
96% at 100% load at rated input voltage.

Control
Main transformer is provided with two 2.5% taps above and below nominal, or one ±5%, depending on kW.

Semiconductors (Diodes)
Diffused silicon diodes are selected to withstand transient voltages and surges without breakdown offering better reliability for motor-load applications.

High grade, hermetically-sealed silicon diodes are mounted on heat sinks and are protected with quick acting silver sand fuses. The PRV rating of all diodes used is a minimum of four times the rated output voltage. These PRV ratings are used for additional transient-voltage protection.

The diodes are pretested for their PRV ratings and leakage current before they are installed into the rectifier unit.

In combining diodes to obtain required output current, adequate provisions are made to insure that no diode will carry current in excess of the safe operating current under any steady state or transient condition. Diodes are conservatively rated to provide ample capacity for overload.

Diode Heat Sinks
The diode heat sink is designed for a conservative temperature rise at full load when proper air flow is maintained throughout the power supply.

The mating surfaces are coated with a heat conductive compound to improve the heat transfer between the rectifier diode and the heat sink. This prevents the formation of galvanic products or oxides between the surfaces. The heat sink is mounted parallel to the direction of air flow with proper baffling provided to assure uniform distribution of air over its cooling surfaces. The heat sink is located in the power supply for easy access when replacing diodes and/or fuses.

Options

Regulated and Unregulated Power Supplies

Transformers - Liquid Filled

• High fire point insulating liquid (RTemp or silicone)
• 55°C rise
• Forced-air cooling
• Winding temperature indicator
• Alarm contacts for gauges
• Pressure relief device
• Sudden-pressure relay
• Input/output air terminal chambers
• Lightning arresters

Transformer (Epoxy Coated)
In addition to vacuum varnish impregnation, the coils of the transformer can be epoxy coated to help make the transformer resistant to severe, environmental conditions.

Available Cooling Options

• NEMA 1 - Convection cooled
• NEMA 3R - Convection cooled
• NEMA 3R - Fan cooled
• NEMA 3S - Water or convection cooled
• NEMA 12 - Water cooled

Common Starting Equipment

AC Magnetic Starter System*
The magnetic starter will include three thermal overload relays, start/stop pushbutton (mounted on the enclosure door), a 110-volt control transformer (if required) for starter coil and a power-on indicating light.

* Call sales office for remote control location.

AC Circuit Breaker
A thermal-magnetic breaker will shut the power supply down in the event of an excessive overload or short-circuit condition. An indicating power-on light will be supplied.

AC Circuit Breaker with Undervoltage Trip
The thermal magnetic circuit breaker will shut the power supply down in the event of an excessive overload, short-circuit condition, an over-temperature condition or an undervoltage condition. A control transformer to power the undervoltage instantaneous trip mechanism and a power-on indicating light will be provided.

AC Circuit Breaker with Shunt Trip
The thermal magnetic breaker will shut the power supply down in the event of an excessive overload, short circuit condition or an over-temperature condition. A control transformer to power the shunt trip mechanism and a power-on indicating light will be provided.

Standard Output Protection DC Circuit Breaker
The two-pole, DC thermal-magnetic circuit breaker will disconnect the load when an excessive DC overload or short circuit condition exists. Three-wire systems are normally supplied with one two-pole breaker.

Fuse Monitoring System
The fuse monitoring system consists of an indicator light connected across each individual fuse. In the event of a fuse failure, the corresponding indicator light will light. The lights are easily viewed through a window located on the front of the enclosure.

Trigger Fuse System
The trigger-fuse system consists of trigger fuses connected across each individual fuse and mounted on a board that will indicate the fuse that has failed.

Regeneration
When DC motors are reversed quickly, or when they rotate because of the load (as occurs when a crane or elevator lowers), excessive back voltages are developed that are impressed across the DC source. In the case of motor-generator units, this excessive voltage is dissipated by circulating through the armature windings. On a DC power supply, it is necessary to furnish such circuitry. This is called a regeneration circuit. This circuit consists of a DC contactor, a resistor bank, and a solid-state automatic control system.

Regeneration Circuit
To insure that the power supply is protected at all times, the Rapid regeneration circuit is designed "fail safe". In other words, the contactor is closed and the resistors are across the output to absorb any back voltage developed while the unit is off. When the unit is energized, the DC contactor opens and keeps the resistor bank off the line. This condition prevails throughout normal operation. When a back voltage is developed, the automatic solid-state control through a precise sensing circuit, closes the regeneration circuit and reduces the rising back voltage before damage can occur to the system. This control is adjustable and the voltage-sensing circuit is normally set between 15 and 20% above the no-load voltage of the power supply for which it is designed. In addition, the regeneration system acts as a dynamic break on an over-hauling load.

The usual rating of the regeneration circuit is 10% of the kW rating of the unit; i.e., 10 kW of regeneration for 100 kW power supply.

Units 150 kW or smaller can have a fixed resistor across their outputs of sufficient size to handle regeneration voltages encountered. Units above 150 kW must use a full automatic regeneration system which includes an intermittent duty or fail-safe continuous duty system. If the power supply is to be used in parallel with others, the sales office should be notified since a slightly different circuit will be utilized.

Regeneration (Continuous)
Available for power supplies of 150 kW or less. A 10 % regeneration is supplied and is always connected.

Regeneration (Intermittent Duty)
Available for power supplies of 3 kW to 2000 kW. The intermittent duty regeneration protects the system at all times, but is automatically connected to the power supply output only when required. Included are the resistor bank (10% regeneration), DC contactor and solid-state control system. Intended for 20% duty cycle with 1 minute maximum on time.

Regeneration (Tracking)
If required, the regeneration circuit can be set to track the output of a regulated rectifier. As the output of the rectifier is adjusted, the regeneration set point is automatically maintained approximately 20% above the rectifier setpoint.

Regeneration (Fail-safe, Continuous Duty)
Available for power supplies above 3 kW. This regeneration protects the system at all times, but is only connected to the power supply when required. Normally rated at 10% of the kilowatt rating of the unit, the resistor bank is sized for continuous duty. In the event of failure of the regeneration detection circuit, the DC contactor would close, putting the resistor bank into the circuit, thereby protecting the motor and rectifier.

Anti-Single Phase Protection System
The anti-single phase protection system will shut the power supply down in the event of a single phase condition. The power supply will not start until the single phase condition is corrected.

The anti-single phase system is normally supplied only when starting equipment is furnished (AC magnetic starter or circuit breaker with undervoltage trip).

If no starting equipment is furnished with the unit, terminals are provided for customer use.

Indoor Drip Proof Enclosure
The drip proof enclosure includes a hood, non-corrosive hardware and gasketed doors and panels.

Outdoor Enclosure
The outdoor weatherproof NEMA 3R enclosure includes a solid top with side fan shutters for forced-air cooling. It include louvers or weather shields for convection cooling. The outdoor enclosure contains non-corrosive hardware and gasketed doors or panels and filters.

Reusable Filters
Reusable aluminum mesh, air-inlet filters will be used. The filters are easily installed and removed without entering the enclosure. Minimum static pressure build-up is achieved with maximum protection against foreign matter intake.

Disposable Filters
The disposable filters are low cost, and are easily installed and removed without entering the enclosure. Minimum static pressure build-up is achieved with protection against foreign matter intake.

Wall Mounting
Brackets may be added to the enclosures for wall mounting - 3 kW to 25 kW only.

Space Heaters
A heater is provided and is energized when the power supply is not operating. Space heaters are used to prevent condensation.

Remote Control
Remote consoles with meters are available.

Analog Meters and Shunt
A voltmeter (4 1/2-inch square), ammeter (4 1/2-inch square) and shunt will be supplied. Both the ammeter and voltmeter are 2.0% accurate. Switchboard type meters with 1% accuracy, or digital meters with better than 1% accuracy are also available.

Switchgear
Rapid can supply AC and DC switchgear configured for the application. The switchgear can be housed in a separate dead front arrangement or can be integral with the power supply.

AC Switchgear
Rapid provides fused and non-fused disconnects as well as high voltage vacuum contactors or circuit breakers.  

DC Switchgear
Rapid is one of the few companies who designs and manufactures DC switchboards. We can supply a simple fixed DC circuit breaker or switch in the power supply, or complete dead front switchgear with drawout breakers and lift device.

Options

Special Programming
Ramp Programming, slow rise, computer control, and other types of controls are available.

Ramp Control
Variable ramp: range or ramp time adjustment from 1% to 100%, of maximum setting. 15 maximum settings available from 12 seconds to 100 minutes.

Computer Interface
Analog and digital interface available for most computer systems. Consult factory for details.

Isolated Signal
When interfacing a power supply with a computer or programmable controller, it is mandatory that all signals to the power supply be electronically isolated from the computer or programmable controller as well as being isolated from each other. Rapid offers a complete line of isolators.

Auto/Manual Switch
Provides the ability to automatically control the power supply from the computer or the PLC or manually with the standard potentiometers. A selector switch is provided to select the desired mode. (0 to 5, 6, 10 volts; 0 to 20 or 4 to 20 mA) plus isolated return signal of voltage. (Iso-amp located at power supply.)

Mercury Arc Rectifier Replacement
This fan-cooled unit is connected to the secondary of the existing transformer. Output voltage adjustment of 240 to 280 VDC is available with ±1% voltage regulation and current limiting.

 

Return to High Power Industrial

Return to Medium Power Industrial