3.1 Installation Safety Requirements

 

Safety Symbols

 

Various symbols may be used on the controller. They have the following meaning:

Refer to manual.

 

Risk of electric shock.

 

Take precautions against static.

 

C-tick mark for Australia (ACA) and New Zealand (RSM).

 

Complies with the 40 year Environment Friendly Usage Period.

 

Restriction of Hazardous Substances

 

Protected by DOUBLE ISOLATION.

 

FM approved logo.

 

 

Dispose of in accordance with WEEE Directive

 

Declaration of conformity to European standard

 

 

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Helpful hints in this manual

 

Personnel Installation must only be carried out by suitably qualified personnel in accordance with the instructions in this manual.

 

Enclosure of Live Parts

To prevent hands or metal tools touching parts that may be electrically live, the controller must be enclosed in an enclosure.

 

Caution: Live sensors

The controller is designed to operate if the temperature sensor is connected directly to an electrical heating element. However you must ensure that service personnel do not touch connections to these inputs while they are live. With a live sensor, all cables, connectors and switches for connecting the sensor must be mains rated for use in 230Vac +15% CATII.

 

Wiring

It is important to connect the controller in accordance with the wiring data given in this guide. Take particular care not to connect AC supplies to the low voltage sensor input or other low level inputs and outputs. Only use copper conductors for connections (except thermocouple inputs) and ensure that the wiring of installations comply with all local wiring regulations. For example in the UK use the latest version of the IEE wiring regulations, (BS7671). In the USA use NEC Class 1 wiring methods.

 

Power Isolation

The installation must include a power isolating switch or circuit breaker. This device should be in close proximity to the controller, within easy reach of the operator and marked as the disconnecting device for the instrument.

 

Overcurrent protection

The power supply to the system should be fused appropriately to protect the cabling to the units.

 

Voltage rating

The maximum continuous voltage applied between any of the following terminals must not exceed 230Vac +15%:

• relay output to logic, dc or sensor connections;

• any connection to ground. The controller must not be wired to a three phase supply with an unearthed star connection. Under fault conditions such a supply could rise above 264Vac with respect to ground and the product would not be safe.

 

Conductive pollution

Electrically conductive pollution must be excluded from the cabinet in which the controller is mounted. For example, carbon dust is a form of electrically conductive pollution. To secure a suitable atmosphere in conditions of conductive pollution, fit an air filter to the air intake of the cabinet. Where condensation is likely, for example at low temperatures, include a thermostatically controlled heater in the cabinet.

 

This product has been designed to conform to BSEN61010 installation category II, pollution degree 2. These are defined as follows:-

 

Installation Category II (CAT II)

The rated impulse voltage for equipment on nominal 230V supply is 2500V.

Pollution Degree 2

Normally only non-conductive pollution occurs. Occasionally, however, a temporary conductivity caused by condensation shall be expected.

Grounding of the temperature sensor shield

In some installations it is common practice to replace the temperature sensor while the controller is still powered up. Under these conditions, as additional protection against electric shock, we recommend that the shield of the temperature sensor is grounded. Do not rely on grounding through the framework of the machine.

 

Over-temperature protection

When designing any control system it is essential to consider what will happen if any part of the system should fail. In temperature control applications the primary danger is that the heating will remain constantly on. Apart from spoiling the product, this could damage any process machinery being controlled, or even cause a fire.

 

Reasons why the heating might remain constantly on include:

• the temperature sensor becoming detached from the process

• thermocouple wiring becoming short circuit;

• the controller failing with its heating output constantly on

• an external valve or contactor sticking in the heating condition

• the controller setpoint is set too high.

 

Where damage or injury is possible, we recommend fitting a separate over-temperature protection unit, with an independent temperature sensor, which will isolate the heating circuit.

 

Please note that the alarm relays within the controller will not give protection under all failure conditions.

 

Installation requirements for EMC

To ensure compliance with the European EMC directive certain installation precautions are necessary as follows:

• For general guidance refer to EMC Installation Guide, which is available from your supplier.

• When using relay outputs it may be necessary to fit a filter suitable for suppressing the emissions. The filter requirements will depend on the type of load.

• If the unit is used in table top equipment which is plugged into a standard power socket, then it is likely that compliance to the commercial and light industrial emissions standard is required. In this case to meet the conducted emissions requirement, a suitable mains filter should be installed.

 

Routing of wires

To minimise the pick-up of electrical noise, the low voltage DC connections and the sensor input wiring should be routed away from high-current power cables. Where it is impractical to do this, use shielded cables with the shield grounded at both ends. In general keep cable lengths to a minimum.