System Power & Environment Requirements

Power Distribution Diagram

The eZMP requires an external DC power source. The power distribution drawing that follows shows an eZMP connected to a SynqNet Drive. The DC power source is connected to the eZMP system through a 3-pin connector. It plugs into the power connector of the eZMP. The ground from the power source and ground from the eZMP must be connected to the Single-Point Ground (SPG).

Figure: Example of 24 VDC power distribution to an eZMP system.

Devices connected to the hardware may have their own power sources for input data or output control signals. You can use other wiring setups, provided that each one is:

at the correct voltage and current levels for the module and the device.
connected to the same Single-Point Ground used by the eZMP.

It is recommended that the same main disconnect switch be used for the eZMP system and for all devices in the application.

Important No matter how the system is installed, before you connect the eZMP to the application, make sure that power is off to the system and to the devices that are wired to the eZMP.

Grounding the System

The ground of the eZMP power source must be connected directly to a Single Point Ground (SPG) tie block. The tie block should be made of brass or copper, bolted or brazed to the control cabinet. If the tie block is bolted rather than brazed, scrape away paint or grease at the point of contact. Put star washers between the tie block and the cabinet to ensure good electrical contact.

Metal enclosures of power supplies, drives, etc., should also have good electrical contact with the SPG.

Caution The Single Point Ground should be the only common point for all the ground lines. If not, ground loops may cause current flow among components of the system which can interfere with proper operation of the eZMP.

Devices to be connected directly to the Single Point Ground include:

Plant safety ground
Chassis ground from eZMP power connector
The metal panel or cabinet on which the eZMP is mounted.
“Common” or “0 V” lines from power supplies that provide external power to the I/O modules and the devices to which they are connected.
Chassis grounds from the devices themselves, such as device drivers, machinery, and operator interface devices.
AC common line from the noise filter, if any.
The ground of the power source of the computer workstation, if any, from which you monitor the system operation. An AC outlet in the control cabinet is recommended.
Single point grounds from other control cabinets, if any, in the system.

ImportantYou must ensure that the “0V” or “Common” of all devices connected to the eZMP are connected to Single Point Ground (SPG). Failure to do so may result in erratic operation or damage to the eZMP. Examples of devices connected to the eZMP include the power source that supplies 24VDC power to the eZMP and devices connected to the eZMP I/O, serial port, or USB ports. Note that some devices (for example, a Personal Computer powered directly from 120/240 VAC) may have their “0V” and “Chassis” connected together internally, in which case only one connection has to be made to SPG for that device.

Also, you must ensure that the eZMP “Chassis” connection is connected to SPG, and that the eZMP is mounted to a metal panel or enclosure that is connected to SPG.

Controlling Heat within the System

The eZMP hardware case is designed with ventilation hole to promote air circulation and dissipate heat. When mounting the eZMP, do not cover or obstruct the ventilation holes and observe minimum clearance requirements specified in the Mounting Instructions section.

Normally, no fans or air conditioners are needed. However, if the environment outside the control cabinet is hot or humid, you may need to use a fan, heat exchanger, dehumidifier or air conditioner to provide the correct operating environment.

Make sure that components installed in the cabinet with the eZMP do not raise the temperature above system limits and that any hot spots do not exceed specifications. For example, when heat-generating components such as transformers, drives or motor controls are installed, separate them from the system by doing one of the following:

Place them near the top of the control cabinet so their heat output rises away from the eZMP.
Put them in another control cabinet above or to one side of the cabinet with the eZMP. This protects the eZMP from both heat and electrical noise.

The eZMP itself is a source of heat, though in most installations its heat dissipates without harmful effects. System heat is generated from power dissipated by:

field side input/output components
other components within the eZMP

Caution If the eZMP is operated outside the recommended limits, it may be damaged. This will void the warranty.

Handling the eZMP-SynqNet

The case protects the eZMP’s internal circuitry against mechanical damage in shipping and handling. However, like any electronics device, the circuitry can be destroyed by:

temperatures over 55° C (131° F)
moisture condensing inside the module
static discharge
exposure to a magnetic field strong enough to induce a current in the circuitry
freezing temperatures, vibration, and other hazards

Recommended Signal Separation

Low level signals (encoder, analog, communications, fast DC inputs) should be separated from high voltage (110 Vac, 220 Vac, 440 Vac, etc.) or high current lines (such as motor armature cables). Maintain at least one inch of separation around signals.

Do not operate transmitters, arc welding equipment, or other high noise radiators within one meter of an enclosure that has the door open. Be sure to equip inductive devices, if they are in series with a mechanical contact or switch, with arc suppression circuits. These devices include contactors, solenoids and motors. Shield all cables that carry heavy current near the system, using continuous foil wrap or conduit grounded at both ends. Such cables include power leads for high-frequency welders and for pulse-width-modulated motor drives.

WarningUse care when wiring I/O devices to the eZMP and when plugging in cables. Wiring the wrong device to the connector or plugging a connector into the wrong location could cause intermittent or incorrect machine operation.