Q: How do I choose between a trip module and PLC-based alarm logic?

Decision rule: who decides, how fast, how independent? Choose a trip module (HS-510, HS-517, HS-540) when: • Alarm/trip decision must happen at the field, next to the sensor , without going through PLC — needing a SIL-compatible safety layer that still works if the PLC network fails. • Local visual indication (LED) and direct relay output is required — to drive a contactor, motor stop, or alarm horn straight from the sensor panel. • A critical machine requires a second independent protection layer (even though primary monitoring goes via PLC). • ATEX area requires field-independent trip capability. Choose PLC-based alarm logic when: • Flexible logic (e.g., two-out-of-two voting, 5-minute averaged trip), trend analysis, SCADA visibility are needed. • Many points must be managed from a single centre. • Signal conditioning via HS-550 PSU + 4-20 mA sensor feeds directly to PLC, with all logic held in PLC code. Most common industry approach: both. Trip module for fast field shutdown (msec range), PLC for trending + maintenance planning. Two-layer protection is the gold standard for predictive maintenance programmes.

Q: 3-channel or 4-channel? How do I choose between HS-530 and HS-535 for multi-channel monitoring?

The decision follows from number of points × number of parameters per sensor . HS-530 (3-channel): One machine with 3 separate vibration channels, or one channel reporting three parameters (e.g., velocity RMS + envelope acceleration + temperature). Typical use: one pump or motor with a triaxial sensor, or three separate bearings. HS-535 (4-channel): Four sensors or four monitoring points handled in one module. Typical use: a four-bearing compressor/turbine, four critical machines on a casting line, or NDE and DE bearings monitored separately. Practical logic: Machines co-located in one room/panel — 4-channel HS-535 is economical (1 module = 4 points). Machines far apart — separate module per point reduces cabling cost. Per-channel output: Both products provide independent 4-20 mA output + alarm relay per channel. So 4-channel HS-535 consumes 4 PLC analog inputs; with ModBus option, one RS-485 cable suffices (all 4 values in one register table). Higher channel count: For large plants, HS-556 (4-channel) and HS-557 (6-channel) offer higher density — during system design, IMB Electric engineering team can optimise points / panel capacity together with you.

Q: How do I migrate charge mode (high-impedance) sensors to IEPE? What does HS-CA001/CA002 do?

Common in legacy plants: a charge mode (high-impedance, picoCoulomb/g output) accelerometer is in place, but the new monitoring system expects IEPE/ICP (2-wire, mV/g output) . The two worlds don't talk directly. Solution: a charge → IEPE converter (HS-CA001 or HS-CA002). How it works: The module receives the high-impedance signal from the charge mode sensor, converts it to mV/g via an internal charge amplifier, then delivers it in 2-wire IEPE format powered by 4 mA constant current. The output is now identical to a standard IEPE sensor — feeds into HS-550 PSU, HS-530 multi-channel module, or directly into a PLC IEPE input card. HS-CA001 vs HS-CA002 difference: • HS-CA001: Single-channel, compact, 1 charge → 1 IEPE conversion. M12 connector input version available. • HS-CA002: Dual-channel, two parallel sensors converted in one module — for panel-dense installations. Typical migration scenario: A 1980–2000-vintage plant with 20 charge mode accelerometers in place, cabling in good condition. Replacing sensors is expensive + requires machine downtime. Solution: Leave the sensors in place, add HS-CA001/CA002 in the control panel, convert charge signal to IEPE, feed to the new monitoring system. Typical cost is 20–30% of full sensor + cabling replacement.

Q: DIN-rail panel architecture: how many modules will I need, and what fits in an HS-580 enclosure?

A typical monitoring panel has these modules on DIN-rail: Per sensor essentials: 1) PSU (HS-550): IEPE supply. One PSU typically powers 1–2 sensors. One per panel often suffices (HS-570-20/40/60 integrate PSU for 2/4/6 sensors). 2) Conversion module (if needed): HS-CA001/CA002 for charge → IEPE. 3) Trip module (optional): HS-510, HS-517, HS-540 — if local alarm is required. 4) Multi-channel module (if multiple sensors): HS-530/535/556/557/558 (for 4–20 mA output consolidation). Sizing example — 4-sensor monitoring panel: • 1× HS-570-40 (4-channel integrated PSU): 1 DIN-rail slot ~50 mm • 1× HS-535 (4-channel monitor): 1 DIN-rail slot ~50 mm • Total: ~100 mm DIN-rail width + power distribution, terminal blocks, fuses. HS-580 Module Enclosure capacity: Polycarbonate IP65, typically holds 8–16 modules (depends on module thickness on standard DIN-rail). Field rule: leave 30% of panel empty — for ventilation + future expansion. For larger plants: HS-CE Connection Enclosure (field junction) + a separate control-room panel (HS-580 or your standard cabinet) supports long-distance cabling.

Q: Sensor power supply: HS-550 or HS-570? How do I size PSU capacity?

IEPE/ICP sensors require a constant current source (typically 2–10 mA) to operate. Hansford offers two options: HS-550 (compact PSU): Powers 1–2 channels, standalone, compact DIN-rail module. Typically preferred for single-point monitoring. HS-570-20/40/60 (integrated PSU): Built-in supply for 2 (HS-570-20) / 4 (HS-570-40) / 6 (HS-570-60) sensors + signal conditioning + input selection option. Ideal for consolidating multiple points into one module — saving cabling and panel space. Sizing: • Each IEPE sensor draws 4 mA (standard). So 6-channel HS-570-60 supplies total of 24 mA. • Typical supply voltage 24 Vdc; PSU converts this to 24 Vdc constant-current mode. • Important: Each sensor line needs sufficient compliance voltage — long cables can drop 4–5 V on the line. The HS-570 family typically provides 18–21 V compliance (handles up to 1000 m of standard cable). Decision table: • 1 sensor → HS-550 economical • 2–3 sensors, compact panel → HS-570-20 or 2× HS-550 • 4–6 sensors, single panel → HS-570-40 or HS-570-60 (all supply in one module) • 6+ sensors → multiple HS-570 + HS-580 enclosure

Q: Signal output: 4–20 mA, ModBus, relay — which goes where?

Modern monitoring modules typically offer three output types , each feeding a different receiver: 1) 4–20 mA analog output (standard): For a continuous vibration value (velocity RMS, acceleration envelope, etc.). Feeds the standard analog input card on PLC/DCS. • Advantage: Universal, simple, noise-immune up to 1000 m. • Limit: Carries one value. Multiple parameters require multiple channels. • Use: Standard trend recording, alarm threshold comparison. 2) ModBus RTU (RS-485, digital): For reading all registers from 10+ modules on a single cable. Optional on HS-535, HS-556, HS-557. • Advantage: One bus, multi-module, multi-channel, multi-parameter. Easy SCADA integration. • Limit: Polling rate limited (typically 100 ms/module). Not suitable for fast trip. • Use: SCADA, MES integration, IIoT gateway. 3) Relay output (alarm): On trip modules (HS-510, HS-517, HS-540, HS-558), the contact opens/closes when a vibration threshold is exceeded. • Advantage: Fast (logic is inside the module, msec response). No PLC needed — goes straight to contactor/siren. • Limit: Binary signal (alarm yes/no). No value transmitted. • Use: Emergency shutdown, alarm horn, local visual warning. Typical practice: The same module simultaneously outputs 4–20 mA (to PLC for trending), relay (to contactor for emergency stop), and ModBus (to SCADA for information). Each output serves a different receiver.

Question 1

How do I choose between a trip module and PLC-based alarm logic?

Accepted Answer

Decision rule: who decides, how fast, how independent?

Choose a trip module (HS-510, HS-517, HS-540) when:
• Alarm/trip decision must happen at the field, next to the sensor, without going through PLC — needing a SIL-compatible safety layer that still works if the PLC network fails.
• Local visual indication (LED) and direct relay output is required — to drive a contactor, motor stop, or alarm horn straight from the sensor panel.
• A critical machine requires a second independent protection layer (even though primary monitoring goes via PLC).
• ATEX area requires field-independent trip capability.

Choose PLC-based alarm logic when:
• Flexible logic (e.g., two-out-of-two voting, 5-minute averaged trip), trend analysis, SCADA visibility are needed.
• Many points must be managed from a single centre.
• Signal conditioning via HS-550 PSU + 4-20 mA sensor feeds directly to PLC, with all logic held in PLC code.

Most common industry approach: both. Trip module for fast field shutdown (msec range), PLC for trending + maintenance planning. Two-layer protection is the gold standard for predictive maintenance programmes.

Question 2

3-channel or 4-channel? How do I choose between HS-530 and HS-535 for multi-channel monitoring?

Accepted Answer

The decision follows from number of points × number of parameters per sensor.

HS-530 (3-channel): One machine with 3 separate vibration channels, or one channel reporting three parameters (e.g., velocity RMS + envelope acceleration + temperature). Typical use: one pump or motor with a triaxial sensor, or three separate bearings.

HS-535 (4-channel): Four sensors or four monitoring points handled in one module. Typical use: a four-bearing compressor/turbine, four critical machines on a casting line, or NDE and DE bearings monitored separately.

Practical logic: Machines co-located in one room/panel — 4-channel HS-535 is economical (1 module = 4 points). Machines far apart — separate module per point reduces cabling cost.

Per-channel output: Both products provide independent 4-20 mA output + alarm relay per channel. So 4-channel HS-535 consumes 4 PLC analog inputs; with ModBus option, one RS-485 cable suffices (all 4 values in one register table).

Higher channel count: For large plants, HS-556 (4-channel) and HS-557 (6-channel) offer higher density — during system design, IMB Electric engineering team can optimise points / panel capacity together with you.

Question 3

How do I migrate charge mode (high-impedance) sensors to IEPE? What does HS-CA001/CA002 do?

Accepted Answer

Common in legacy plants: a charge mode (high-impedance, picoCoulomb/g output) accelerometer is in place, but the new monitoring system expects IEPE/ICP (2-wire, mV/g output). The two worlds don't talk directly.

Solution: a charge → IEPE converter (HS-CA001 or HS-CA002).

How it works: The module receives the high-impedance signal from the charge mode sensor, converts it to mV/g via an internal charge amplifier, then delivers it in 2-wire IEPE format powered by 4 mA constant current. The output is now identical to a standard IEPE sensor — feeds into HS-550 PSU, HS-530 multi-channel module, or directly into a PLC IEPE input card.

HS-CA001 vs HS-CA002 difference:
• HS-CA001: Single-channel, compact, 1 charge → 1 IEPE conversion. M12 connector input version available.
• HS-CA002: Dual-channel, two parallel sensors converted in one module — for panel-dense installations.

Typical migration scenario: A 1980–2000-vintage plant with 20 charge mode accelerometers in place, cabling in good condition. Replacing sensors is expensive + requires machine downtime. Solution: Leave the sensors in place, add HS-CA001/CA002 in the control panel, convert charge signal to IEPE, feed to the new monitoring system. Typical cost is 20–30% of full sensor + cabling replacement.

Question 4

DIN-rail panel architecture: how many modules will I need, and what fits in an HS-580 enclosure?

Accepted Answer

A typical monitoring panel has these modules on DIN-rail:

Per sensor essentials:
1) PSU (HS-550): IEPE supply. One PSU typically powers 1–2 sensors. One per panel often suffices (HS-570-20/40/60 integrate PSU for 2/4/6 sensors).
2) Conversion module (if needed): HS-CA001/CA002 for charge → IEPE.
3) Trip module (optional): HS-510, HS-517, HS-540 — if local alarm is required.
4) Multi-channel module (if multiple sensors): HS-530/535/556/557/558 (for 4–20 mA output consolidation).

Sizing example — 4-sensor monitoring panel:
• 1× HS-570-40 (4-channel integrated PSU): 1 DIN-rail slot ~50 mm
• 1× HS-535 (4-channel monitor): 1 DIN-rail slot ~50 mm
• Total: ~100 mm DIN-rail width + power distribution, terminal blocks, fuses.

HS-580 Module Enclosure capacity: Polycarbonate IP65, typically holds 8–16 modules (depends on module thickness on standard DIN-rail). Field rule: leave 30% of panel empty — for ventilation + future expansion.

For larger plants: HS-CE Connection Enclosure (field junction) + a separate control-room panel (HS-580 or your standard cabinet) supports long-distance cabling.

Question 5

Sensor power supply: HS-550 or HS-570? How do I size PSU capacity?

Accepted Answer

IEPE/ICP sensors require a constant current source (typically 2–10 mA) to operate. Hansford offers two options:

HS-550 (compact PSU): Powers 1–2 channels, standalone, compact DIN-rail module. Typically preferred for single-point monitoring.

HS-570-20/40/60 (integrated PSU): Built-in supply for 2 (HS-570-20) / 4 (HS-570-40) / 6 (HS-570-60) sensors + signal conditioning + input selection option. Ideal for consolidating multiple points into one module — saving cabling and panel space.

Sizing:
• Each IEPE sensor draws 4 mA (standard). So 6-channel HS-570-60 supplies total of 24 mA.
• Typical supply voltage 24 Vdc; PSU converts this to 24 Vdc constant-current mode.
• Important: Each sensor line needs sufficient compliance voltage — long cables can drop 4–5 V on the line. The HS-570 family typically provides 18–21 V compliance (handles up to 1000 m of standard cable).

Decision table:
• 1 sensor → HS-550 economical
• 2–3 sensors, compact panel → HS-570-20 or 2× HS-550
• 4–6 sensors, single panel → HS-570-40 or HS-570-60 (all supply in one module)
• 6+ sensors → multiple HS-570 + HS-580 enclosure

Question 6

Signal output: 4–20 mA, ModBus, relay — which goes where?

Accepted Answer

Modern monitoring modules typically offer three output types, each feeding a different receiver:

1) 4–20 mA analog output (standard):
For a continuous vibration value (velocity RMS, acceleration envelope, etc.). Feeds the standard analog input card on PLC/DCS.
• Advantage: Universal, simple, noise-immune up to 1000 m.
• Limit: Carries one value. Multiple parameters require multiple channels.
• Use: Standard trend recording, alarm threshold comparison.

2) ModBus RTU (RS-485, digital):
For reading all registers from 10+ modules on a single cable. Optional on HS-535, HS-556, HS-557.
• Advantage: One bus, multi-module, multi-channel, multi-parameter. Easy SCADA integration.
• Limit: Polling rate limited (typically 100 ms/module). Not suitable for fast trip.
• Use: SCADA, MES integration, IIoT gateway.

3) Relay output (alarm):
On trip modules (HS-510, HS-517, HS-540, HS-558), the contact opens/closes when a vibration threshold is exceeded.
• Advantage: Fast (logic is inside the module, msec response). No PLC needed — goes straight to contactor/siren.
• Limit: Binary signal (alarm yes/no). No value transmitted.
• Use: Emergency shutdown, alarm horn, local visual warning.

Typical practice: The same module simultaneously outputs 4–20 mA (to PLC for trending), relay (to contactor for emergency stop), and ModBus (to SCADA for information). Each output serves a different receiver.

Question 7

How is trip logic set up in an ATEX hazardous area?

Accepted Answer

When implementing vibration monitoring and trip logic in an ATEX area (Zone 1/2/21/22), answer three questions:

1) Sensor side — Ex protection type:
• Ex ia (Intrinsically Safe): Safe by low-energy principle. Sensor + IS barrier (on control-room side) + certified cable. The most common solution.
• Ex d (Flameproof): Heavy metal housing that contains any explosion internally. Ex d sensors are more expensive but require no IS barrier.

2) Trip module side — Certification:
The trip module itself stays in the safe area (control room, Zone 0/non-hazardous). It receives the sensor signal through the IS barrier, runs the logic, and outputs the relay. HS-517I variant is specifically designed for ATEX installations — featuring IS-compatible input and approved earthing architecture.

3) Trip gate — what logic should run:
In an ATEX plant, safety logic typically must be SIL-compliant (Safety Integrity Level), under ISO 13849 or IEC 61508. The trip module's relay output is wired in de-energize-to-trip mode — meaning if a cable breaks or power drops, the alarm fires (fail-safe).

Typical installation: Zone 1 motor bearing with Hansford HS-150 IS sensor → IS barrier (HS-AA022) → Zone 0/safe control room with HS-517I trip module → relay output opens motor contactor.

For site-specific ATEX trip architecture design, contact IMB Electric engineering team.

Question 8

Panel installation: environmental protection (IP), cable entry, mounting — practical recommendations?

Accepted Answer

Treat modules as being inside a panel, sensors on the field side. Environmental protection is planned separately for each side.

HS-580 Enclosure (field side or control room):
• Polycarbonate body, IP65. Outdoor installation acceptable (with UV-shading sunshade recommended).
• Internal temperature: -25 to +60°C. Under direct sunlight, it can exceed 70°C — add a sunshade or passive vent.
• Cable entry: Sealed via cable glands (M16/M20). For multiple sensors, several glands at the bottom.
• Layout: Horizontal DIN-rail, modules sequenced top-left to right (in the direction of wiring).

HS-CE Connection Enclosure (field junction):
• IP65/IP67, for consolidating sensor cables on the field side.
• Typical use: 2–4 sensors from one machine consolidated at a junction, then one multi-conductor cable to the control room.
• Cabling cost is reduced 40–50% (one thick cable for long distance, instead of many thin ones).

HS-IJE Intrinsically Safe Junction Enclosure (ATEX field):
• IP66, ATEX-certified, blue IS cable entry.
• Mandatory as a sensor junction in hazardous areas (standard HS-CE is not ATEX-certified).

Practical recommendations:
• Passive vent at top of cabinet — modules generate heat, closed panels see temperature rise.
• Fuse + main isolator inside the panel — for maintenance personnel.
• Label every terminal and cable. To isolate a single sensor fault fast.
• Reserve 30% panel space empty — for future expansion.

About the Hansford Vibration Systems and Switches series

01How do I choose between a trip module and PLC-based alarm logic?

023-channel or 4-channel? How do I choose between HS-530 and HS-535 for multi-channel monitoring?

03How do I migrate charge mode (high-impedance) sensors to IEPE? What does HS-CA001/CA002 do?

04DIN-rail panel architecture: how many modules will I need, and what fits in an HS-580 enclosure?

05Sensor power supply: HS-550 or HS-570? How do I size PSU capacity?

06Signal output: 4–20 mA, ModBus, relay — which goes where?

07How is trip logic set up in an ATEX hazardous area?

08Panel installation: environmental protection (IP), cable entry, mounting — practical recommendations?