In industries such as oil and gas, chemical processing, mining, and industrial manufacturing, a small electrical spark can become a serious safety hazard. When flammable gases, vapors, or combustible materials are present, electrical equipment must be designed to reduce the possibility of becoming an ignition source.
This is where intrinsic safety plays an important role.
Intrinsic safety is a protection technique based on limiting the electrical and thermal energy available in a circuit so that it cannot cause ignition under the conditions covered by the applicable protection level and certification.
For battery-powered equipment, this presents a particular challenge: a battery is designed specifically to store and deliver energy. Creating an intrinsically safe battery solution therefore requires careful control of how that energy can be released—even when faults occur.
At PHD Energy, we work with OEMs developing battery-powered equipment for hazardous locations, including applications that require certified intrinsically safe battery solutions.
Understanding Ignition Sources in Hazardous Locations
A hazardous location is an environment where an explosive atmosphere may be present because of flammable gases, vapors, mists, or combustible dusts.
Potential ignition sources from electrical equipment can include:
- Electrical sparks and arcs
- Short circuits
- Excessive current
- Hot components or surfaces
- Battery faults
- Connector faults
- Electrostatic discharge
- Component failures
A conventional battery-powered device may contain enough stored electrical energy to create a spark or excessive temperature during certain failure conditions.
The battery, protection circuitry, enclosure, wiring, connectors, and the rest of the electrical system must be evaluated as part of the equipment's overall protection concept.
Intrinsic Safety Starts With Energy Limitation
Unlike some protection methods that focus on containing the effects of an ignition, intrinsic safety is fundamentally based on preventing sufficient ignition-capable energy from being available in the first place.
This can involve controlling several parameters, including:
| Parameter | What the design controls |
|---|---|
| Voltage | Limiting electrical potential within relevant circuits. |
| Current | Restricting the amount of current that can flow, including during fault conditions. |
| Power | Controlling the total electrical power available to components and circuits. |
| Stored energy | Evaluating energy stored in batteries, capacitors, inductors, and other components. |
| Temperature | Ensuring components and accessible surfaces remain within applicable temperature limits. |
The exact requirements depend on the equipment, hazardous-location classification, protection level, applicable standard, and certification strategy.
Why Batteries Require Special Attention
Batteries make intrinsic-safety engineering particularly interesting because their primary purpose conflicts, at first glance, with the intrinsic-safety philosophy.
A battery needs to store enough energy to operate a device for hours—or sometimes days. Intrinsic safety, meanwhile, requires potentially hazardous energy to remain controlled.
How do you provide the energy the device needs while preventing that energy from creating an unacceptable ignition risk?
This can require a combination of carefully selected cells, current-limiting components, redundant protection, thermal protection, mechanical design, and fault-tolerant circuitry.
Depending on the required protection level, the system may also need to remain safe when specified faults are applied during evaluation.
Battery-powered applications
Three examples show why battery design belongs in the hazardous-location protection strategy.
Portable Gas Detector
Consider a worker carrying a portable gas detector into an oil and gas facility.
The detector itself is intended to warn the worker about hazardous gases, but its battery and electronics must also be appropriate for the hazardous environment in which the detector operates.
If a circuit fault creates a spark with sufficient energy, the safety device itself could potentially become an ignition source.
An intrinsically safe design controls available electrical and thermal energy so that the equipment meets the applicable requirements for its certified hazardous-area use.
This is why battery design is an important part of developing intrinsically safe gas detection equipment.
Industrial Handheld Device
Technicians working around chemical plants, refineries, or other hazardous locations increasingly rely on portable electronic equipment for inspections, communications, data collection, and maintenance.
These devices may require substantially more battery capacity than a simple sensor.
More capacity, however, means more stored energy.
The challenge is not simply selecting a battery with the longest runtime. Engineers must consider how the battery behaves during normal operation and under applicable abnormal and fault conditions.
A properly engineered intrinsically safe battery system can help an OEM achieve the necessary balance between runtime, performance, and hazardous-location protection requirements.
Industrial IoT Sensor
Many industrial facilities are deploying wireless sensors in locations that were previously difficult or expensive to monitor.
A remote sensor may need to operate from a battery for months or even years while installed in an area where a flammable atmosphere can occur.
In these applications, battery selection affects far more than runtime.
Engineers may need to consider maximum voltage, available short-circuit current, protection components, operating temperature, cell chemistry, enclosure design, and the energy available elsewhere in the circuit.
This makes the battery system an important part of the overall intrinsic-safety design strategy.
Intrinsic Safety Is More Than Adding a Protection PCB
One common misconception is that adding a battery protection circuit automatically creates an intrinsically safe battery.
It does not.
Conventional battery protection circuits are typically designed to protect against conditions such as overcharge, over-discharge, overcurrent, and short circuits. These are important battery safety functions, but intrinsic safety introduces additional requirements related to ignition prevention and fault behavior.
Depending on the design and applicable standard, an intrinsically safe battery solution may require features such as:
- Multiple independent protection mechanisms
- Current-limiting components
- Voltage limitation
- Temperature monitoring
- Thermal protection
- Carefully selected cells
- Controlled component ratings
- Fault-tolerant circuit architecture
- Mechanical protection
- Evaluation under specified fault conditions
This is why intrinsic-safety requirements should ideally be considered early in the product development process, rather than after the battery and electronics have already been finalized.
How PHD Energy Supports Intrinsically Safe Battery Applications
PHD Energy works with OEMs developing battery-powered equipment for demanding industrial and hazardous-location applications.
For products requiring intrinsic-safety protection, we can support projects with certified battery solutions and custom battery-pack engineering, depending on the application's specific requirements.
Our battery engineering approach can consider factors such as:
- Required voltage and capacity
- Maximum current
- Cell chemistry and cell selection
- Protection architecture
- Redundant safety mechanisms
- Thermal protection
- Mechanical configuration
- Operating temperature
- Hazardous-location requirements
- Applicable certification strategy
Certified battery solutions
Where an existing PHD Energy certified battery meets the application's requirements, OEMs may be able to start with an established battery platform rather than beginning every aspect of battery development from scratch.
Custom battery design
For applications with unique electrical, mechanical, runtime, or environmental requirements, PHD Energy can also work with customers on a customized battery solution.
Designing Safety Into the Power Source
Intrinsic safety is fundamentally about controlling potential ignition sources before they can ignite a hazardous atmosphere.
For battery-powered equipment, that means thinking beyond basic battery safety.
Engineers must consider where electrical and thermal energy is stored, how that energy can be released, what happens when components fail, and how the complete system behaves under the fault conditions required by the applicable standard.
The result is a battery system designed not only to power the equipment, but also to support the equipment's hazardous-location protection strategy.
