1. Overview

The Pe series motor pre-start purge control system (hereinafter referred to as the purge control system) is mainly used for increased safety Exe, sparkless Ex n and non-flammable motors. As an increased safety measure, pre-purge before starting can reduce the possible flammable gas concentration in the housing before the motor starts to below the safety line.
This system can be used not only for internal ventilation and purge control of large motors in hazardous locations, but also for internal ventilation and purge control of other electrical equipment. The system controls the purge pressure, purge flow and purge time to quickly purge the flammable gas that may exist inside the motor before starting.

For electrical equipment working in Zone 2 specified in GB3836.14-2014, it is impossible for explosive mixtures in the form of gas, steam, mist (if they occur, they only occur occasionally and exist for a short time) or explosive dust mixtures (only in a fault state) to occur during normal operation. In this case, the electrical equipment pre-start purge system can be used to ensure the safe operation of the electrical equipment.
Explosion-proof mark: Ex db eb IIC T6 Gb

2. System composition

The pre-start purge control system consists of three parts: a control unit, a wiring unit and a pressure relief unit. The outer shell is made of stainless steel wire drawing process.

3. Product Features

The pre-start purge control system is fully pneumatically controlled, and all components are imported international products, which are stable, reliable and durable.

4. Model meaning

5. Principle and Selection Guide

The main control unit of the Pe-type motor pre-start purge control system controls the supply of compressed gas and confirms the purge flow, pressure and time. The pressure relief unit serves as a safe outlet for the equipment purge gas and provides a signal to confirm the flow parameters of the motor cavity gas. The motor pre-start purge control system sets the purge flow and time according to the motor model to ensure that the gas in the shell is purged and ventilated as required for safety before each start of the motor, avoiding the unreliable factors of manual operation. When the ventilation is completed, the signal (contact switch or pneumatic signal) is linked to send the motor start permission.

When selecting the model, the user should select the purge flow according to the size of 5 times the electrical housing volume. Generally, the purge time takes at least 20 minutes and the longest takes 45 minutes, usually 30 minutes. For example: the housing volume of an electrical equipment is 12000NL, and the purge flow calculation method is: 12000NLX5/30min=2000NL/min. It is more appropriate to select 2000 NL/min for the purge orifice plate flow. The definition of electrical enclosure volume in item 3.5 of GB3836.52004 is the volume of the empty enclosure without internal equipment. For rotating electrical machines, it refers to the internal net volume plus the volume occupied by the rotor.

6. Main technical parameters

　　Control unit technical parameters

Wiring unit technical parameters

Outlet interface: M20×1.5 (reference), ExeⅡ cable entry device.

Pressure relief unit technical parameters

7. Dimensions

(See Pd type dimensions)

8. System Installation Diagram

7. Wiring Diagram

10. Installation

For the installation of the Pe type motor pre-start purge system control, refer to the system installation diagram. In front of the air source input port of the purge device, install a G1" ball valve as the air inlet valve for easy debugging. Before connecting the air source inlet of the purge device, open the air inlet valve to blow air to ensure that there are no impurities in the air inlet pipe, and then connect the air inlet pipe. Before turning on the air source switch, check the outlet of the pressure relief valve to ensure that it is unobstructed.

11. Use

After the pre-start purge control system is debugged, there are two ways to use it normally: local start or remote solenoid valve start.

1. Local start: In the main control unit, turn the local switch from the "run" position to the "reset" position until the purge light turns yellow (usually 2~5s). After the purge light turns yellow, turn the switch back to the run position.

2. Remote solenoid valve start: The main control room sends out the excitation voltage of the local solenoid valve 24VDC for 2~5s.

Regarding the two start-up methods, local start-up is mainly used for system debugging. For normal use, remote solenoid valve start-up is recommended. The main control room controls it uniformly. When the motor needs to be started, a signal (24VDC 2~5s) is sent to the purge device. When the purge is completed normally, the signal is sent back to the main control, and the motor is started immediately. In this way, the purge is completed to the motor start-up is coherent and the time is controllable.

12. Maintenance

1. Check whether the air source pressure, flow rate and cleanliness meet the requirements.

2. Check the function of the purge flow sensor. There is a pressure side pilot on the pressure relief valve, which can be connected to a micromanometer or a U-type water pressure gauge. At the beginning of each purge, when the purge indicator turns yellow, the pressure value should be at least 10mbar. During daily use, regular inspections are required.

3. The main control single source built-in filter is usually maintenance-free, and needs to be inspected once a year to clean or replace the core.

4. The fire-blocking net under the pressure relief valve should be inspected regularly to ensure smooth flow.

13. System Advantages

Advantages of Huaye explosion-proof instrument automatic purge device:

1. Fast response speed

The scientific gas circuit design, the scientific combination of mode amplification and nozzle baffle technology, further expands the low-pressure response performance of the valve, and adopts the diaphragm large ring arc design, which greatly improves the sensitivity of the sensor to micro-pressure response, making the system dynamic response performance excellent, leakage compensation response rapid, and follow-up performance agile.

2. Strong stability and high reliability

Relying on the technical strength of the pneumatic laboratory, boldly innovate the gas circuit design, strive to design simple, reasonable and scientific, and adopt international products such as Bellofram, MAC, and BARTEC in the United States, so that the product has strong stability and high reliability. It can be said that the product performance indicators are comprehensively improved.