VersaPro Temperature Controller
Page 8
Copyright © 2013, United Process Controls Inc.
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2.3
Enclosure of live parts
To prevent hands or metal tools touching parts that may be electrically live, the controller should be installed in
an enclosure. The contacts on the rear of the instrument case or finger save but it is still possible for loose
wiring, or metal objects to come in contact with live terminal connections. It is recommended that power be
removed from the instrument connections before they are disconnected. However, instrument’s power
connector can be removed with power applied. Care should be taken that the connector does not come in
contact with any grounded object.
2.4 Live
sensors
The dc inputs, dc logic, and dc outputs are all electrically isolated from chassis ground. If the temperature
sensor is connected directly to an electrical heating element then the inputs will also be live. The controller is
designed to operate under these conditions. However you must ensure that this will not damage other
equipment connected to these inputs and that service personnel do not touch connections to these terminals
while they are live. With a live sensor, all cables, connectors and switches for connecting the sensor and non-
isolated inputs and outputs must be mains rated.
2.5 Wiring
It is important to connect the controller in accordance with the wiring data given in this handbook. 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 for
installations comply with all local wiring regulations. For example, in the UK, use the latest version of the
wiring regulations, BS7671. In the USA use NEC Class 1 wiring methods.
2.6 Power
Isolation
The installation must include a power isolating switch or circuit breaker. This device should be in close
proximity to the control actuator, and within easy reach of the operator. There is no means of disconnecting
power from the instrument other than removing the connectors from the rear of the instrument. It is
recommended that additional power disconnects are provided in the installation to remove power from these
connectors as well.
2.7
Earth leakage current
Due to RFI Filtering there is an earth leakage current of less than 0.5mA. This may affect the design of an
installation of multiple controllers protected by Residual Current Device, (RCD) or Ground Fault Detector,
(GFD) type circuit breakers.
2.8
Over Current protection
The instrument has an internal 3.15 Amp fuse (P/N MFU-3.15PCTT) for instrument power and 1 Amp fuses
(P/N MFU-1.0PCTT) for the control contacts and alarms. It is recommended that additional protection against
excess currents be used for loads exceeding this rating. Fusing and interposing relays should be added to the
control circuit if high current or large inductive loads are used.
