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S11 Series Switching Amplifiers

These amplifiers are normally intended for large systems. They are based on a half bridge, FET switcher PWB, the OUT-11 which is rated at 1,000 VA.  

Instruments, Inc. has delivered over 14,000 OUT-11 PWBs since 1987. The reliability of the OUT-11 has been very good. Actual experience has proved greater than a 290,000 hour MTBF per Output PWB.

A pair of boards forms a full bridge. Fast rectifiers and drivers are used for maximum efficiency. Full modulation control is allowed. The transistors are fully protected against load faults, excessive switching frequency, cooling failure, and start-up or power-down transients.

The various models of amplifiers are designated S11-xxm where xx is the number of output boards and m is an optional modifier for special applications. These amplifiers are complete, having a suitable power supply, input preamp and an output filter/transformer system.

Amplifier

Models smaller than the S11-8 are rack mounting, therefore the size and weight is for the amplifier only. The models S11-8 and larger are delivered in a structure (rack), therefore their size and weight is the total and includes the "rack". Multiple cabinets may be designed into a system. We have delivered 3 systems each consisting of 8 S11-64 amplifiers connected to a single load. 

The output transformers in models S11-2 through S11-24 are usually mounted from the front. These transformers may be designed for operation down to 50 Hz, however this reduces the high frequency performance and increases the weight slightly. In addition, models smaller than the S11-32 may be designed as specials to pass through a submarine hatch. The larger models have rear mounted transformers which operate down to 300 Hz and are not designed for submarine use.

Model S11-2A is a 2kVA output stage contained in a chassis consisting of minimal metalwork. It is intended to be mounted in a larger chassis, perhaps with other units for a multi-channel system. This output stage does not have a power supply or output transformer, but does include output filtering.

Model S11-36D and S11-36U are multi-channel amplifiers having 18 separate inputs with 18 separate outputs of 2,200 VA each. The output voltage and current from each channel is monitored during the output burst. Values are stored internally in the PM/FL computer and accessable via a front panel switch and displayed on front panel meters. The last known values are displayed until the next burst. These amplifiers are shock mounted for shipboard use.

Interface

The Interface function is accomplished with an analog Pre-Amp, analog output voltage and current monitors, and digital Fault Detection and Fault Location information. If needed, a summing transformer is included for unusual load matching and/or high voltage output.

Power Supply

In our switching amplifiers, reactive currents are returned to the power supply. Thus, when driving a load with a power factor of 0, either capacitive or inductive, the power drawn from the primary AC source is only 15% of the output VA. Any real power delivered to the load increases the primary AC power. With a resistive load, at full power, the overall efficiency is about 75%.

The power supply may be regulated or unregulated.  When a regulated supply is used, the DC voltage will be at the rated voltage for the output PWBs, resulting in the maximum output VA possible.  Our regulated supplies have a power factor of 70%.

Our unregulated supplies have the advantage of a power factor of 94-98% at full load.  The disadvantage of an unregulated supply is that the maximum rated voltage for the output PWBs is established at high line and no load.  At low line and full load, the DC voltage is less, therefore the available output VA of the amplifier is less.

 


OUT-11 1 kW Half Bridge Switching PWB.

(Click image to enlarge)

Specifications for Standard S11 Series Amplifiers

Type of amplifier

Full bridge equivalent, FET output, Switching

Modulation

Squarewave, Stair-Step, or PWM

Load power factor range

0 - 100% capacitive or inductive

Distortion (THD)

PWM: 2% max, 0.2% typical.

Frequency range (-3 dB)

PWM: STD

300 Hz to 20 kHz

 

 

or 600 Hz to 40 kHz

 

PMW: LF

50 Hz to 5 kHz

 

Stair-Step: max sw freq

160 kHz

RMS noise (PWM only)

-60 dB gated on

- - below max output

-120 dB gated off

Current monitor

100 mV/A

Voltage monitor

2 mV/V

Protection

No combination of passive loads, input signals or

 

switch settings will cause amplifier failure.

Fault lights

Temp limit, voltage limit, current limit, blown fuse

Ambient temperature

0 - 40 degrees C

Primary power (standard)    

S11-2, 4

208/240 V 60 Hz 1ph

Contact factory for

S11-8 - 24

208/240 V 60 Hz 3ph

other AC voltages

S11-32 - 64

480 V 60 Hz 3ph

 


Individual Specifications

Model designation

S11-2A

S11-2

S11-4

S11-8

S11-16

S11-24

Output watts - continuous

1,000

1,000

2,000

4,000

8,000

12,000

- 100 sec burst @ 20%

2,000

2,000

4,000

8,000

16,000

24,000

Width (inches overall)

6

19

19

24.5

24.5

24.5

Depth (inches overall)

15

22

22

29.5

29.5

29.5

Height (inches overall)

5

14

22.75

49

62

75

Weight, std

10

140

200

600

1,200

1,400

Weight, low freq (pounds)

NA

170

275

725

1,500

1,750

 

 

Amplifier Photograph

S11-2A

S11-2

S11-4

S11-8

S11-16

S11-24


Model designation

S11-32

S11-36D/U

S11-48

S11-56

S11-64

Output watts - continuous

16,000

8 sec on

24,000

28,000

32,000

- 100 sec burst @ 20%

32,000

18 x 2,200

48,000

56,000

64,000

Width (inches overall)

24.5

23.6

24.5

24.5

24.5

Depth (inches overall)

38

25.6

38

38

38

Height (inches overall)

57

67.8

69

75

81

Weight (pounds)

1,600

970

2,000

2,200

2,400

Amplifier Photograph

S11-32

S11-36D

S11-48

S11-56

S11-64


Models with an "A" have no cabinet, power supply, or output transformer.
Models with a "B" have no power supply.

Some models are available in a Multi Channel configuration.
S11-36D or U are 18 channels of 2.2kVA each.
Dimensions with shock mounts and stabilizer 26.0 x 27.3 x 75.9 1050 lb.

Contact the factory for special design limitations and cost.

Specifications and prices subject to change without notice.

 

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