On the Safety of Stage Machinery from the Design Perspective(Outline)

CHEN Wei

（Design and Research Institute of the General Armaments Department, Beijing 100028, China）

On the Safety of Stage Machinery from the Design Perspective(Outline)

CHEN Wei

（Design and Research Institute of the General Armaments Department, Beijing 100028, China）

In this paper, domestic and international safety standards and specifications related to the design were introduced, as well as the safety design of general theater audience, stage, electrical control system and special equipment. In addition, it was illustrated by specific examples.

stage machinery; safety design; safety standards; dafety standards; theatre

1 Foreword

Stage machinery is a kind of professional equipment configured for theaters according to specific functional needs and built environment as conditions. Stage machinery is not a simple application of industrial machinery on the stage. It is inextricably linked with the theater's own functions and integrated with the internal environment. In old theaters, stage machinery is used for setting the stage and changing scenery. And in modern theaters, stage machinery is a must in order to make ever-changing arena or incredible changes, no matter the construction is grand or simple, no matter on the stage or behind the scenes. Today, stage machinery has become the integrated support of modern technology. It is the focus of choreography, lighting, sound, video, viewers, special effects, actors, props and the director, the link between all kinds of sports. However, the meaning of the existing of all these existence is safe!

Different characteristics between stage machinery and traditional modern industrial machinery:

(1)High degree human-computer integration;

(2)Diversification: diverse forms, functions and clients;

(3)Great timeliness in using;

(4)Large individual differences, more new equipment in short-term, the lack of experimental verification.

2 Safety design specifications and standards

“Safe” refers to the statement that danger not occurring to people or things in a certain environment. And“safety” refers to the level of damage that people or things can withstand the most in a certain environment.

The ultimate goal of safety is to avoid accidents. Currently, our country has the compulsory market entry certification system for 3C products; the safety production controlling system (“safety system” for short) is set in the automated system of industrial devices; the level of the set and safety requirement are prescribed.Instrument Society of American (ISA) called safety system as Safety Instrument System (SIS), corresponding to the standard ISA-S84.01. International Electrotechnical Commission (IEC) called safety requirement level as Safety Integrity Levels (SIL), corresponding to the standard IEC61508.

So how to distinguish the safety level of devices? How to design the devices to achieve to safety requirement?

2.1 The European Machine Safety Standard

According to the European Machine Safety Standard EN 954-1, firstly, risk rating is necessary before design to make sure the danger level of the machine (or any part of it). The danger level is divided into 5 rising levels: B, 1, 2, 3, 4. Level 4 is the highest danger level.

According to the danger level, certain measures are determined to lower the risks, for example, mechanical structural design, safety protection and safety control circuit.

The safety control circuit design must conform to the required safety level. Corresponding to the European Safety Standard Machine EN 954-1, the safety level of control circuit is divided into 5 levels: B, 1, 2, 3, 4, corresponding with the 5 danger levels. But the safety level is uprising from B to 4. Level 4 is the highest safety level. For example, the danger level of a machine (or any part of it) is level 4, then the corresponding safety level of safety control circuit must be level 4.

2.2 Existing safety standards in our country

Our specification of the risk assessment undertakes the safety iterative process, the process of risk assessment for all kinds of risks in the lifetime of the machine. Now, there are still no safety evaluation criteria domestically. We only have certain standards in petrochemical industry: petrochemical emergency shutdown and safety interlocking System Design Guidelines (SHB-Z06-1999) adopts the concept of SIL by IEC and is called degree of safety. It has quantitative criteria, for instance, SIL 2 is defined as the annual average rate of risk of failure is 0.01 to 0.001.

2.3 Domestic safety norms and standards in arena industry

2.4 International arena industry safety norms and standards

3 Safety design of regular theater equipment

Over the years, the stage design of our theater is in strict accordance with specifications. In some cases, combining with operational requirements, relevant technical indexes are even higher than regulatory requirements to ensure the safety of devices.

3.1 Devices under Stage: lift, pan, rotating devices etc.

(1)Structural safety

(2)Drive safety

(3)Travel safety

(4)Other safety facilities

·Latch.

·Anti-shearing device.

·Protective net.

·Safety door.

·Safety railing.

·Devices interlock protection.

3.2 Platform hanging equipment

The same as the audience equipment, stage equipment configures a number of security facilities according to their craft and sports properties.

(1)Structural safety

Whether the rod structure does prescribed uniform load or concentrated loads, the deformation volume is within the standard range (no more than hanging point span 1/200).

(2)Drive safety

Choose S1 duty motor, power calculation consider acceleration and leave a reasonable margin.

With independent double brake. Each brake motor rated torque is not less than 1.25 times of the rated torque.

Rope safety factor are controlled more than 10 times, the speed point hoists and equipment, it is to reach or exceed 12 times.

Set windlass matsunawa (stacked rope, arbitrary justice) testing.

(3)Load safety

Windlass rely on current detection load to inspect whether it is overloaded or install physical sensor payload to measure the size of the load in real time. At the field devices commissioning phase, all 125% load test is performed.

(4)Travel safety

In addition to the soft limit, a limit switch and an overrun switch are also installed. Also, use a limit switch as zero switch to calibrate the position of the boom.

3.3 Measures to achieve electrical control system security

To prevent errors, for all safety-related functions with hazard identification risk assessment, necessary safety level (SIL) of the stage machinery control system should be determined by the principles of mechanical safety risk assessment, and then determine technical requirements in accordance with relevant safety and select the appropriate security measures.

3.3.1 Electrical equipment protection

(1) Ground fault / residual current protection;

(2) Phase sequence and phase loss protection;

(3) Overcurrent protection caused by short circuit;

(4) The overcurrent protection;

(5) Abnormal temperature protection;

(6) Supply interruption or voltage drop protection subsequent recovery;

(7) The motor stall, over-speed protection;

(8) Over-voltage caused by lightning or switching surges;

(9) Controlling power supply with IT power supply.

3.3.2 Electromagnetic compatibility (EMC) Protection

Protective measures are:

(1) Ground and shielding;

(2) Electromagnetic decoupling and filtering;

(3) Elimination of static electricity;

(4) Soft start;

(5) The motor and electromagnetic actuator assembly cable should be independent of the other cable routing;

(6) To ensure that the drive control cabinet has interrupter contact function;

(7) The resettlement process of EMC when design and control cubicle partition.

3.3.3 Software programming

(1) Questions that should be considered in general installation and environment;

(2) The target object and measuring amount controlled by the user;

(3) Total system response time;

(4) Diagnose of failure, identification of failure, alarm recording, alarm processing;

(5) Interlock: physical requirements, system type, manual override, and password authorized access control;

(6) Stop: The system power, system backup, normal shutdown, emergency shutdown;

(7) Start: restart, cold start, warm start;

(8) Operator Interface: key locks, software lock, the access control and security plans needed for operator’s intervention.

3.3.4 Emergency shutdown

3.3.5 Safety interlock

3.3.6 Mature control secunty technology

4 Safety design of special equipment and case

4.1 Functional requirements

There are theaters requiring the audiences to act during the show changes, beyond the conventional concept of theater play model, which aims at:

Implement changes in performance mode or angle;

Achieve interaction between the actor and the audience;

Achieve the audience’s dynamic experience.

For equipment over the audience and movable audience or auditorium seating units, because it is closely related to security of the general audience, its safety should be above ordinary stage equipment.

4.2 Security Design

(1) Design guidelines: ensure full conditions of safe evacuation, security failure type. (2) Safety analysis, safety assessment and safety control

4.3 Success Cases

4.3.1 3D flying apparatus of Xinjiang Grand Theatre altitude (above the auditorium)

4.3.2 Mobile auditorium of Wuhan Wanda Chinese show theater

4.3.3 Vibrate auditorium of Jiuzhaigou eternal love theater

4.3.4 Safely isolated power station of Xinjiang Grand Theatre tankers

5 Problems and Suggestions

5.1 Safety issues

(1)Human-computer diversity and standard basis;

(2) Waterproof, moisture-proof and anti-shock;

(3) Uncertainty of prop’s parameters and load prediction mechanism

(4) Limitation of detection and the importance of the subject of management system;

(5) Difficulties of electromagnetic compatibility with other professionals, especially dimming, SCR andhigh harmonics;

5.2 Safety codes and standards to improve

(1) Recommend the forced integration;

(2)Promote the concept of security level;

5.3 Supporting mechanism of safety specification implementation

(1) Safety norms and standards of oversight mechanisms;

(2) The measures implemented to ensure the safety norms;

(3) Market economy recognition and conversion;

The implementation of designing safety codes require technology, equipment, materials , time cycle of design and other investments in aspects, which can emerge value under market condition .Backward technology, and equipment with poor safety materials are not safe without doubt .The level of security should be corresponded with the grade of market value.

Stage machinery safety is a long-term discussion. From the point of usage, we are concerned about the combination of technology and art.

However, from the perspective of implementation, we are more concerned with the degree of functional and security assurance. "Maverick “and "fatigued" have continually been setting challenges before us, but the red line of security always accompanies us, which is like "two wings of a bird, two wheels of a bike."

Only under careful control, cautious processing can our industry be healthy, orderly and in steady development!

Chen Wei：

Deputy director and senior engineer of engineering design & research institute of the General Armaments Department Stage Equipment Research And Development Center. Engaged in the theatre stage, stage machinery equipment research design for many years. Successively engaged in dozens of large theatre stage technology design and research like National Grand Theatre, Ningbo, Guangzhou opera houses, Beijing's Poly Theater, etc. Published more than ten relating dissertations, gained 5 national invention patents.

（编辑 杜 青）