PACE-DSA Series

Multichannel dynamic signal acquisition unit

Most of the mechanical faults worth finding in high-voltage plant announce themselves in vibration long before they show up anywhere else. The limit is rarely the diagnosis. It is having a front end quiet enough, fast enough and isolated enough to record the signature at all.

Four models · 4 or 8 IEPE channels · 204.8 kSps · isolated USB · under 6 W

Selected & supported by HVPACE

Where the diagnostic content sits, against the band over which this instrument's performance is specified. Transformer, tap changer and mechanism work falls inside it. Acoustic partial discharge does not — which is a question to settle before ordering, not after.

At a glance

4 / 8

IEPE input
channels

204.8

kSps maximum
sample rate

>116 dB

input SNR,
20 kHz band

<1.2 µV

residual noise,
20 kHz band

What it acquires

The PACE-DSA is not a diagnostic instrument in itself. It is the front end that sits between the sensor and whatever analysis you run afterwards — and on mechanical signature work the front end is usually what decides whether the fault is visible at all. Everything it records is a voltage; what makes it useful on power plant is how quietly it does that, and what it will connect to without a signal conditioner in between.

Acceleration from IEPE accelerometers. Every analog input carries 24 V / 4 mA constant-current conditioning, so a standard IEPE accelerometer connects by coaxial lead with nothing between it and the converter.
Acoustic signals from IEPE microphones and contact sensors. The same conditioning drives airborne and structure-borne acoustic sensors, within the bandwidth discussed below.
Voltage from any source inside ±11.2 V peak. Coil current shunts, current clamp outputs, travel transducers and auxiliary contact voltages, on inputs that can be set to DC or AC coupling channel by channel.
A speed or trigger reference on the counter input. Acquisition can be aligned to a plant event or a shaft reference rather than to the moment the operator pressed record.
Two analog outputs for stimulus. When the measurement is a frequency response rather than a passive recording, the same unit drives the exciter.

Why these numbers matter

The host interface is galvanically isolated. A substation earth and a laptop earth are rarely at the same potential, and the difference between them is exactly the sort of thing that appears in a recording as a fault you then spend an afternoon chasing. Isolation on the USB side removes that path.
Residual noise below 1.2 µVrms. A loosening core clamp or a mechanism starting to bind produces a small change in a signal that is already small. When the signature is not visible, the limit is nearly always the noise floor of the acquisition, not the analysis applied afterwards.
Sample rates to 204.8 kSps at 32-bit word length. The word length sets the transport format; the usable dynamic range is set by the SNR figure of better than 116 dB, which is what to compare against other front ends.
IEPE and coupling selectable per channel. An accelerometer on one input and a coil current shunt on the next, in the same record and on the same timebase, without a separate conditioner.
Fanless, 12 V DC at under 6 W. No fan noise into an acoustic sensor, and a unit that will run from a field battery for a day of recordings.
Reference clock input and output, plus external trigger. Acquisition can be locked to an external timebase or started from a plant event rather than by hand.

Choosing a configuration

One measurement platform in four part numbers. The choice is channel count, and whether the unit presents itself to the host as a vendor device or as a standard USB audio-class device.

Table 1

PACE-DSA configurations

Part number	Analog inputs	IEPE channels	Host interface
PACE-DSA-04	4	4	Standard
PACE-DSA-04A	4	4	USB audio-class
PACE-DSA-08	8	8	Standard
PACE-DSA-08A	8	8	USB audio-class

← scroll the table sideways to see all columns

Host interface. The A versions enumerate as a standard USB audio-class device, which means the host recognises them with no vendor driver installed and they can be recorded by generic software on Windows, macOS or Linux. That is worth having where the recording machine is not yours to configure — a site laptop under someone else's IT policy, for instance. Tell us which host you have to work with and we will confirm which version to order.

Accessories. DC 12 V supply with NZ/AU plug set, 2 m BNC coaxial leads, 100 mV/g IEPE accelerometer with magnetic base, and a foam-lined transit case. Ordered separately against the unit.

Technical specification

Table 2

Analog input

Parameter	PACE-DSA-04	PACE-DSA-08
Connector	4 × BNC, single-ended or differential	8 × BNC, single-ended or differential
IEPE conditioning	4 channels, 24 V / 4 mA	8 channels, 24 V / 4 mA
Input range	±1 V / ±10 Vp (maximum 11.2 Vp)	±1 V / ±10 Vp (maximum 11.2 Vp)
Coupling	DC or AC, selectable per channel	DC or AC, selectable per channel
Input impedance	500 kΩ single-ended / 1000 kΩ differential	500 kΩ single-ended / 1000 kΩ differential
Sample rate	44.1 – 204.8 kSps	44.1 – 204.8 kSps
Word length	32-bit	32-bit
Signal-to-noise ratio	> 116 dB (20 kHz BW, ±10 Vp range)	> 116 dB (20 kHz BW, ±10 Vp range)
THD+N	< −110 dB (20 kHz BW, 10 Vp, 1 kHz)	< −110 dB (20 kHz BW, 10 Vp, 1 kHz)
Residual noise	< 1.2 µVrms (20 kHz BW, 50 Ω)	< 1.2 µVrms (20 kHz BW, 50 Ω)
Amplitude flatness	±0.01 dB, 20 Hz – 20 kHz	±0.01 dB, 20 Hz – 20 kHz
Amplitude accuracy	±0.05 dB (15 – 30 °C ambient)	±0.05 dB (15 – 30 °C ambient)

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Read the bandwidth qualifier. Every performance figure above is specified over a 20 Hz – 20 kHz measurement bandwidth. At the maximum sample rate the Nyquist limit is 102.4 kHz, so content above the specified band is digitised — but its amplitude is not covered by the accuracy and noise figures quoted. Transformer, tap changer and breaker mechanism work sits comfortably inside the specified band. Acoustic partial discharge does not. If that is what you are measuring, ask us to confirm the response at the frequency you need before you order rather than after.

Table 3

Analog output

Parameter	Specification
Connector	2 × BNC, single-ended or differential
Single-ended range	±1 V / ±10 Vp
Differential range	±2 V / ±20 Vp
Signal-to-noise ratio	> 120 dB (20 kHz BW, 10 Vp range)
THD+N	< −110 dB (20 kHz BW, 10 Vp, 1 kHz)
Drive capability	Minimum load 600 Ω
Output impedance	50 Ω single-ended / 100 Ω differential
Amplitude flatness	±0.01 dB, 20 Hz – 20 kHz
Amplitude accuracy	±0.05 dB (15 – 30 °C ambient)
Coupling	DC

← scroll the table sideways to see all columns

Table 4

Digital I/O, host interface and supply

Parameter	Specification
Counter input	1
PWM generator	1
Reference clock input	1
Reference clock output	1
Digital I/O	4
External trigger	Supported
Host interface	USB, galvanically isolated
Power supply	DC 12 V, < 6 W
Operating temperature	0 °C to +40 °C, fanless convection cooling
Storage temperature	−20 °C to +60 °C
Relative humidity	10 – 90 %, non-condensing
Case (PACE-DSA-04)	150 × 130 × 35 mm (D × W × H), under 0.7 kg

← scroll the table sideways to see all columns

Specifications are typical at 23 °C unless stated otherwise. Case dimensions for the eight-channel models are confirmed at quotation.

Where it fits

Transformer tank and core vibration. Clamping condition and winding looseness, from the 100 Hz component and its harmonics.
On-load tap changer vibro-acoustic signature. Contact timing drift and spring energy loss, from the transient burst of a tap operation.
Circuit-breaker and disconnector mechanism vibration. Latch, damper and linkage condition on an operation, alongside or instead of a timing test.
GIS mechanical signature capture. Where the enclosure prevents a direct view of the mechanism and the structure-borne signal is what you have.
Rotating plant. Station service fans, pumps and generators, with a tacho reference on the counter input.
Modal testing and frequency response. Using the analog outputs as the stimulus source.

On why a mechanism signature is worth recording at all, and what it shows that a timing test does not: WP-02, Breaker vibration diagnostics. For the field triage step that comes before instrumented acquisition, see WP-01, Mobile video acoustic triage.

Supply & support

Manufactured in China and supplied under the HVPACE part number. Selected, supplied and technically supported by HVPACE, Auckland. Twelve-month warranty from delivery; calibration and application support provided locally for New Zealand and Australia. Commissioning support, measurement set-up and operator training available on request.

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About HVPACE

HVPACE is the trading name of Power Asset Condition Engineering Limited, a New Zealand-based supplier of test and diagnostic instruments and selected specialty equipment — such as cable sheath voltage limiters and other low-volume, mission-critical components — for high-voltage power systems. Backed by hands-on engineering expertise, including field-tested condition assessment techniques and AI-based signal analysis, we support customers with diagnostic guidance, methodology development and fault investigation, so they get the most value from the equipment they buy.

Enquire about the PACE-DSA

Web hvpace.co.nz · Technical papers papers.hvpace.co.nz · Engineering tools tools.hvpace.co.nz
Email [email protected] · Phone +64 21 0259 6074 · Auckland 0616, New Zealand

HVPACE is the trading name of Power Asset Condition Engineering Limited (NZBN 9429053607218), Auckland, New Zealand.
Specifications are subject to change without notice. Confirm current configuration at time of order.