DESCRIPTION

The SPAH Series "Pulsating" Synchro Power Amplifiers, and DSPH Series High Power Digital to Synchro Converters, are proven, high efficiency, low cost, compact, reliable solid state synchro drivers; designed for demanding Naval/Maritime, Aircraft, fire control and Radar/Antenna related, applications. They are commonly used on synchro based data transmission, re-transmission, simulation, and instantaneous absolute position indicating and active control systems.

The SPAH series accept any 3 wire synchro, or 4 wire sine/cosine resolver inputs, the DSPH Series accept up to 16 bits of parallel binary data inputs, either providing an efficient high power 3 wire synchro output, capable of driving direct and multiple large synchro loads. Models range from 25VA continuous/ 100VA peak, 50VA/200VA peak, 100VA/400VA peak, and 150VA /600VA peak selections standard product, and up to 300VA /1000+VA peak units can be provided on special app's.

All Models are completely powered from the AC reference input, eliminating the need for any large and very expensive (heat generating) linear DC supplies.

Installation is easy: in most synchro booster- amplifier, repeater, and retransmission applications; simply treat it like a synchro; mount it, wire your 5 synchro source leads, 3 synchro destination leads, and your running !

For High power D-S applications; the digital to synchro converter is built into, and completely powered by the amp.. To install D-S units, simply apply your 14 or 16 bit digital TTLdata in lieu of synchro input and your running. The input is continuos and the input to output throughput is less then 100 Usec. D-S options include; Data Latch inputs for synchronous  or strobed data transfer, and high-byte/low-byte latched enable inputs for use with either an 8 or 16 bit data bus.

Optimum effeciency is achieved by essentially using as much AC direct power transfer as possible to drive the AC outputs; because there is no DC conversion in the power transfer, and the amplitude of the internal AC power rails need only be a few volts greater than the voltages driven on the outputs.

Because the outputs are allowed to follow the reference input (synchro's and converters use ratio accuracy), these supplies only need to be a small percentage higher in voltage then the amplifiers maximum output voltage to accomodate the headroom required of the circuit.

The lower the voltage differential required input to output (considering the internal transformers), to drive the load; the minimum the power loss (in the form of heat), and the greater the efficiency of the amp.

Because there is no internal high frequency PWM or charge-pump switching; there is no RF switching noise emmitted from the unit, or discontinuities in the outputs, to compromise other user circuits, and the outputs are inherently compatible with all and any existing synchro converters.

Using this type of "dynamic power transfer technique", the efficiency is nominally better then 80%, and loss (power dissipation & heat generation) for reactive loads is less then half that of conventional DC powered amplifiers.

Care should be taken to minimize the phase shift between the reference and signal inputs. Since the power supplies are only a few vols higher than the signal, the output could be affected by phase shift. Phase shift effect, compansation, and management techniques are detailed in CCC app. note#G-SA1 "Driving Synchro Loads".
 

Packaging/Conductive Cooling

These models are all self-contained in a easy to install "Bolt-On" bulkhead mount chassis. The chassis is a light weight, singlepiece aluminum, 1/8" thick solid base plate, that provides excellent thermal transfer for conductive cooling of the unit.

Mounting and Thermal Considerations:

Since the unit is primarily conduction cooled, make sure that it is tightly mounted to an appropriately large, thermally conducive (unpainted) surface. Thermal grease can also be applied to the mounting surface.

Kick Circuit

For Torque Receiver applications a kick circuit is provided to free stalled rotors, simply wire a jumper between the "CO" (current overload) output, and the "Kick" input.

More common an occurance with large digital or switched step inputs, or after power up; a synchro torque reciever may get hung up at a false null, and just sit there and vibrate while draining large circulating currents. The amplifier will sense the overload that occurs if the rotor is persistantly drawing too much current trying (unnsuccessfully) to move the shaft load, and (with the kick/CO jumper installed) the amp. will automatically shift the output by 120 degrees for a nominal 1/2 second duration to free the rotor from the false null.

Once the rotor is put in motion it has greater control control of its output. Use this feature only if at least one Torque Receiver is being driven from the outputs.

Disable Input

The disable input is a TTL compatable Opto-Isolated input used to provide a circuit-safe means of disabling (turning off & on) the amplifier outputs for various applications. When dissabled the outputs appear as an open circuit to the load.

The dissable can be used to sequentially power up the synchro amps. if several are used in a power sensative application, or when used where the the synchro signal outputs are going through switching relays for auxilliary, back-up, or test systems.

By disabling the outputs prior to switching either the reference/power inputs or the stator outputs, or both, and then driving the synchro-amp. inputs to match the angle dictated on the destination source prior enabling the outputs; the relays can very safely switch these points without any appreciable power demand during the actual switching. This will provide a very smooth transition that will reduce surges, and inductive content, allowing the user to minimize the required size of the re
lays, and dramatically increase the life of any relays used for switching these (high power) terminations.

A logic 1 is used to disable the power outputs, a logic 0 will enable the outputs providing the unit is powered and is not in a thermal overload sensed condition.

BIT Output

The Built-in-test output is a TTL compatible Opto-Isolated output that uses a logic level 1 to indicate that the amplifier has sensed either a thermal overload condition forcing it to shut down its outputs until the internal temperature cools down, or a current overload that is straining and thereby distorting the outputs, until the load is recovered (or kicked to free a stalled rotor), or if in thermal overload (when the internal temperature sense shuts down the outputs).

Current-Load Sense

The output current on 25VA units is limited to 1.0 amp peak, and approximitely 1 amp/25VA on larger units, after a 4 second nominal delay; an overcurrent indication is sensed, setting the BIT output to a logic 1 (See Built-in-test, above).

When Driving Torque Receivers, the current limmiting is typically experienced whenever the rotor is off null (any significant difference in angle, from where it is being commanded to go), typically activating the kick circuit to rapidly set the driven synchro in motion (to free the rotor from hang-up), allowing the rotor to move towards its commanded angle (= null).

Thermal Sense

These synchro amplifiers are thermally protected, the amplifier outputs will shut down when the internal temperature reaches 125^oC, also setting the BIT output to a logic 1. Thermal overload recovers when the internal temperature recovers.

~~~~~~~~~~~~SPECIFICATIONS~~~~~~~~~~~~~~~

DC Power Input for Logic Output Supply:+5V D.C. +10% @ 10ma MAX.(Not Required on -P units, add a P to the end of P/N)

Digital Inputs/Outputs: (All Units)

*Disable...Input (DIS).: Logic "0" = L= OVDC Enables Power Amplifier Output, TTL Compatible,requires 2.5ma. at logic O
** Isolation: OptoIsolated - 1000V Peak min. Break-down voltage to Ground.

Built-in-Test..Output, Overload Indicator (BIT),: logic
level 1= H, drives 2 TTL loads, indicates amplifier sensed over load condition forcing it to shut down its outputs until conditions are satisfied (see txt).
** Isolation: OptoIsolated - 1000V Peak min. Break-down voltage to Ground.

Kick Circuit: Kick & CO (kick input & current over load); are normally connected for Torque Receiver Loads (not for Passive CT or CDX loads); If Output is Hhung-up due to excessive current output; Shifts output 120^O for .5 sec. to unjam rotor hang-up.(see txt.)

Notes:
*1)Providing unit is not in thermal overload; internal Temperature is less then 125^OC.
*2) Synchro Outputs when disabled are as open circuit, high impedence state.
**3) On D-S units (having internal Digital to Synchro Converter); no external +5VDC is required, uses internal isolated +5VDC supply, the +5VRTN (see block dia.) is same as the digital data common only.

SIGNAL INPUTS:

Synchro: 90V L-L 400Hz +10% Impedence = 400K Ohms min. balanced
Synchro: 90V L-L 60Hz +5% Impedence = 100K Ohms min. balanced
Synchro: 11.8V.L-L @ 400Hz.+ 10% Impedence = 26K Ohms min. balanced
Resolver: 6.81V L-L @ 400Hz. +10% Impedence = 4K Ohms min. balanced
Resolver: 6.81V L-L @ 60Hz +5% Impedence = 4K Ohms min. balanced
 

SIGNAL INPUT ISOLATION: Internally Transformer Isolated; 500VDC min. Breakdown Voltage to Gnd.

SYNCHRO OUTPUTS:

Synchro Output: 90V. Output Models: 90V L-L +1%:
25VA Models: Drives Zso = 243 Ohms (Passive CT & CDX type loads)
Drives Zss = 6 Ohms (Active Torque Receiver type loads)
 

*REFERENCE POWER INPUT:

** 90V.Signals, 25VA Models:
(400 Hz.) 115V. RMS +10%, 360-440 Hz. @ 50 ma.
(60 Hz.) 115V. RMS +10%, 57-63 Hz.. @ 50 ma.
(60 & 400) 115V. RMS +10%, 57-440 Hz. @ 50 ma.

Notes:
*1)Reference input must be in phase with signal inputs and signal outputs
**2) (No load) plus 1 ma. per ma. of output load.
3) Units can be provided with internal or external  S-D/D-S converters to allow frequency conversion or tolerate inputs having a different reference source then the output signal's reference source, in all cases the synchro output reference source must be the same ultimate source used to power the unit.

MODEL SELECTION GUIDE FOR SYNCHRO BOOSTER (AMPLIFIERS)

NOTES:
1)Add -p to end of model# for units with internal +5VDC power supply, (no external supplies required)
2)Use 6.81V. signal inputs when driven by ISA,VME, or STD Bus D-S cards using +/-15VDC supplies
*3) Consult factory

CCC app. note#G-SA1
 "Driving Synchro Loads".

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