Why Choose the ABB CM-IWS.1P Insulation Monitoring Relay?
The ABB CM-IWS.1P (1SVR740660R0100) is a compact and reliable insulation monitoring relay designed to supervise insulation resistance in unearthed electrical distribution systems. Part of ABB's CM-IWS measuring and monitoring relay range, it helps identify insulation deterioration and earth faults in industrial electrical installations before they develop into more serious operational problems.
The CM-IWS.1P is designed for unearthed IT AC, DC and mixed AC/DC systems with nominal system voltages up to 250 V AC or 300 V DC. It operates from a wide-range 24–240 V AC/DC control supply and provides an adjustable insulation resistance threshold from 1–100 kΩ, with precise adjustment in 1 kΩ increments.
Featuring a superimposed square-wave measuring principle, interrupted measuring-wire detection, configurable fault storage and one changeover (SPDT) output contact, the relay provides dependable insulation fault signalling. Its ABB Easy Connect push-in terminals, three LED indicators and compact 22.5 mm DIN rail housing make it suitable for industrial control cabinets, isolated power systems and electrical distribution applications.
Key Advantages
- Reliable insulation resistance monitoring for unearthed IT electrical systems.
- Suitable for AC, DC and mixed AC/DC networks within the specified voltage limits.
- Monitors systems up to 250 V AC or 300 V DC.
- 24–240 V AC/DC control supply offers flexibility across industrial installations.
- Adjustable insulation resistance threshold from 1–100 kΩ.
- Precise threshold adjustment in 1 kΩ increments.
- Superimposed square-wave measuring principle supports reliable insulation supervision.
- Interrupted measuring-wire detection helps identify monitoring circuit faults.
- Configurable fault storage and latching through a control input.
- One changeover (SPDT) output contact for alarm and control signalling.
- Closed-circuit operating principle supports fault-responsive relay operation.
- Three LED indicators provide clear operating and fault status information.
- ABB Easy Connect push-in terminals simplify installation and wiring.
- Compact 22.5 mm DIN rail housing conserves electrical cabinet space.
- Designed for insulation monitoring according to IEC/EN 61557-8.
Key Features
- ABB CM-IWS.1P insulation monitoring relay.
- Manufacturer order code: 1SVR740660R0100.
- Rated control supply voltage: 24–240 V AC/DC.
- Monitored system types: Unearthed IT AC, DC and mixed AC/DC systems.
- Maximum nominal monitored AC voltage: 250 V AC.
- Maximum nominal monitored DC voltage: 300 V DC.
- Insulation resistance measuring range: 1–100 kΩ.
- Threshold adjustment resolution: 1 kΩ.
- Measuring principle: Superimposed square-wave signal.
- Continuous supervision of insulation resistance to earth.
- Interrupted measuring-wire detection.
- Configurable fault storage and latching through a control input.
- Output configuration: 1 changeover (SPDT) contact.
- Operating principle: Closed-circuit principle.
- Status indication: 3 LEDs.
- Terminal technology: ABB Easy Connect push-in terminals.
- Maximum system leakage capacitance: 10 µF.
- Suitable for single-phase control circuits and compatible three-phase main circuits.
- Housing width: 22.5 mm.
- DIN rail mounting for industrial electrical panels.
- Insulation monitoring according to IEC/EN 61557-8.
Technical Specifications
- Manufacturer: ABB
- Product series: CM-IWS
- Model: CM-IWS.1P
- ABB order code: 1SVR740660R0100
- ABB product group: 310921-Measuring & Monitoring Relays
- Product type: Insulation monitoring relay
- Rated control supply voltage: 24–240 V AC/DC
- Monitored network type: Unearthed IT systems
- Compatible network configurations: AC, DC and mixed AC/DC
- Nominal monitored AC system voltage: 0–250 V AC
- Nominal monitored DC system voltage: 0–300 V DC
- Insulation resistance measuring range: 1–100 kΩ
- Threshold adjustment: 1 kΩ increments
- Measuring principle: Prognostic measurement using a superimposed square-wave signal
- Maximum system leakage capacitance: 10 µF
- Interrupted measuring-wire detection: Yes
- Fault storage: Configurable via control input
- Fault latching: Configurable
- Output contacts: 1 changeover (SPDT) contact
- Operating principle: Closed-circuit principle
- UL/CSA contact rating: B300
- Maximum output operating voltage (UL/CSA): 300 V AC
- Status indication: 3 LEDs
- Terminal type: Easy Connect push-in terminals
- Connection technology: Screwless spring-clamp connection
- Housing protection rating: IP50
- Mounting type: DIN rail mounting
- Insulation monitoring standard: IEC/EN 61557-8
- Operating ambient temperature: −25 to +60 °C
- Storage temperature: −40 to +85 °C
- Dimensions (H × W × D): 85.6 × 22.5 × 103.7 mm
- Net weight: 0.137 kg
- EAN: 4016779852647
- Customs tariff number: 85364900
Reliable Insulation Monitoring for Unearthed IT Electrical Systems
The ABB CM-IWS.1P continuously monitors insulation resistance between the active conductors of an unearthed electrical network and earth. In an IT earthing system, the supply is isolated from earth or connected through a sufficiently high impedance. This arrangement can allow continued operation after a first insulation fault, provided the installation is designed and managed appropriately.
Insulation monitoring is particularly important in these systems because a developing earth fault may not produce sufficient current to operate conventional overcurrent protective devices. The CM-IWS.1P helps identify a reduction in insulation resistance and provides an output signal when the configured threshold is reached.
The relay uses a prognostic measuring principle with a superimposed square-wave signal. This enables the device to assess insulation resistance in compatible unearthed AC, DC and mixed AC/DC systems, including AC systems with galvanically connected DC circuits.
With a nominal monitored voltage range of 0–250 V AC or 0–300 V DC, the CM-IWS.1P is suitable for a variety of low-voltage isolated electrical systems. The monitored network must remain within the device's specified voltage and leakage capacitance limits.
Adjustable Insulation Thresholds and Fault Detection
The CM-IWS.1P provides an adjustable insulation resistance threshold from 1–100 kΩ, allowing engineers to configure the alarm response according to the monitored installation. Threshold adjustment in 1 kΩ increments supports precise commissioning.
When the insulation resistance falls below the configured response value, the relay changes its output state to indicate an insulation fault. This signal can be used by an industrial control system to activate a warning, inform maintenance personnel or initiate a suitable protective response.
The relay also includes interrupted measuring-wire detection, helping identify a disconnected monitoring connection that could otherwise prevent reliable insulation supervision.
Configurable fault storage and latching allow detected fault conditions to be retained when required by the application. This can be useful where maintenance personnel need to investigate an intermittent insulation fault after the monitored resistance has returned to an acceptable level.
Straightforward Integration with Industrial Control Systems
The ABB CM-IWS.1P features one changeover (SPDT) output contact operating according to the closed-circuit principle. The output can be connected to suitable PLC inputs, alarm circuits and electrical control systems to communicate insulation fault conditions.
Its three LED indicators provide convenient visual information about the operating condition of the relay, supporting fault identification and routine maintenance.
ABB's Easy Connect push-in terminals simplify wiring by using spring-clamp connections instead of conventional screw terminals. This supports consistent electrical connections and efficient installation in industrial control cabinets.
The compact 22.5 mm DIN rail housing makes the CM-IWS.1P suitable for installations where panel space is limited. The device is designed for insulation monitoring according to IEC/EN 61557-8 and should be installed in accordance with ABB's wiring instructions and the applicable electrical installation standards.
Typical Applications
- Insulation resistance monitoring in unearthed IT electrical systems.
- Earth fault detection in isolated AC distribution networks.
- Insulation supervision in unearthed DC systems.
- Monitoring mixed AC/DC electrical networks.
- Industrial electrical control circuits.
- Compatible three-phase unearthed distribution systems.
- Electrical distribution panels and industrial switchboards.
- Manufacturing and process automation equipment.
- Industrial power supplies and isolated control systems.
- PLC-based insulation fault signalling and alarm systems.
- Electrical maintenance and insulation condition monitoring.
- OEM machinery with unearthed electrical supply systems.
- Applications requiring early detection of deteriorating insulation.
- Installations requiring configurable insulation fault latching.
