Dwyer MTL5045 - Manual (Page 8)

4 INM5000-6 Jul 2010
3.1.5. Relay outputs
Reactive loads on all units with relays should be adequately
suppressed.Changeover relay outputs are provided on the following
units: MTL5011B, MTL5014, MTL5018 and MTL5314. In order to
achieve maximum contact life, a minimum switching current of 10mA at
≥5V is recommended.
3.1.6 Earth leakage detection
An MTL4220 earth leakage detector can be used with a number of
MTL5000 Series units to detect hazardous-area earth faults which can
then be rectified without needing to shut down the loop ('no-fail'
operation). On units with a single-channel input, the MTL4220 is
connected to terminal 3 and on units with two-channel inputs, to
terminals 3 and 6. Units which can be used with an MTL4220 are:
MTL5011B MTL5012 MTL5014 MTL5015
MTL5017 MTL5018 MTL5021 MTL5022
MTL5023 MTL5024 MTL5025 MTL5061
N.B. HAZ1-3 or HAZ4-6 connectors are required.
3.1.7 Ambient temperature considerations
Ambient temperature limits for unenclosed MTL5000 Series isolators are
from -20°C to +60°C with units close-packed.
4 ACCESSORIES
4.1 MTL5000 power bus - Installation
and use
4.1.1 MTL5000 Series power bus
Power bus kits provide facilities for linking the power supply terminals
(13 and 14) of up to 32 installed MTL5000 Series units to a standard
24V power supply. Buses consist of chains of power plugs and are
available in different lengths to suit various numbers of modules as
follows:
4.1.2. Installation
4.1.2.1
Check to make sure the bus length is correct for the
number of modules involved.
4.1.2.2 If the number of modules is less than the maximum number
the chain will support, cut off the surplus power plugs at
the tail end of the chain - leaving a 'new' tail end.
4.1.2.3 Insert power plugs into the power terminals on the safe-
area side of each module in sequence.
4.1.2.4 Connect the power supply source to the tail end of the
chain (using the insulation displacement connectors
(Scotchloks) provided if required).
Notes: 1. To reduce the risk of excessive voltage drop or over-
current, DO NOT connect power buses in series.
2. Surplus sections can be used (and, if required)
connected together provided the cut ends are safely
terminated and/or connected together. Use single
ferrules with a crimp tool or insulation displacement
connectors (Scotchloks). Suitable ferrules and connectors
are provided with the kits.
4.2 Earth rail and tagging accessories
This section explains how to specify and assemble earth rail and tagging
strip accessories for the MTL5000 Series.
The accessories consist of mounting brackets, earth rails, tagging strips
and associated parts. They provide facilities for earthing, terminating
cable screens and tagging (identifying) the positions of individual units.
4.2.1 Parts list
IMB57 Insulating mounting block (figure 4.5)
One required at each end of a tagging strip/earth rail. Suitable for low-
profile (7.5mm) and high-profile (15mm) symmetrical DIN rail.
ERB57S Earth-rail bracket, straight (figure 4.6)
Nickel-plated; supplied with two push fasteners, one earth-rail clamp
(14mm, 35mm
2 ) and one earth cable clamp (10mm, 16mm 2 ).
Note: ERB57S is the preferred choice of earth-rail bracket. It is usually
fitted in the upper slot on insulating mounting block IMB57.
Number of modules Kit ID code
(contains grey power plugs for 24V dc supply)
1 to 8 PB-8T
9 to 16 PB-16T
17 to 24 PB-24T
25 to 32 PB-32T
– +
Optional insulation
displacement
connectors
x2
OR
Figure 4.1: Installing a chain of power plugs into MTL5000
Series modules
Figure 4.2: Using crimp ferrules or insulation displacement
connectors (Scotchloks) to terminate cut ends