Printable page one (pdf) | Printable page two (pdf)

Increased Safety - Type "e"

The RCH/e range of electric Cord Heaters was designed specifically for use with Increased Safety Type "e" Electric Motors.
The RCH/e provides low cost protection against condensation within rotating electrical equipment.

Typical applications would be electric motors, generators and alternators which operate in damp or wet condition.

Examples would include off shore, shipboard and marine equipment, dockside cranes, well pumps and all equipment operating in a tropical environment.

Specifying anti-condensation heaters at the design stage can save the expense of costly rewinds and down time.




Resistance Technology: RCH/e measurements


The heating unit is designed for inclusion in the impregnation process.


By the OEM or a Rewinder on a stock motor:
the heater should be bound on the windings, as discussed page 2, then heavily coated with varnish and allowed to cure and then a second heavy coat applied. (To ensure that the heater and windings form a homogenous mass to provide good thermal conductivity).

By a Rewinder:
as part of the rewind process where the heater will be fully impregnated with the windings.

Resistance Technology: RCH/e Joint
BASEEFA Component Certificate
BAS No. Ex 98E3248U

The component is coded EEx e II
(BS EN 50014: 1993)
(BS EN 50019: 1994)

ATEX Certificate No

The component is coded:
ExII 2 G EEx e II



RCH Type


Volts Watts
0a/e 305 110 7
0b/e 305 240 7
1a/e 432 110 12
1b/e 432 240 12
2a/e 686 110 20
2b/e 686 240 20
4a/e 762 110 22
4b/e 762 240 22
5a/e 1016 110 29
5b/e 1016 240 29
6a/e 1067 110 30
6b/e 1067 240 30
7a/e 1473 110 42
7b/e 1473 240 42
8a/e 1702 110 48
8b/e 1702 240 48

240V Heaters are suitable for 230V and 220V supply voltage
110V Heaters are suitable for 115V supply voltage


1) Accommodating Standard Length Motor Heaters

The heating unit is designed for inclusion in the impregnation process.

It is possible to apply Type RCH/E heaters to a number of different winding diameters on the principle that the length of a particular heating unit or units will cover at least 70% of the circumferential distance and if an overlap occurs, that the client will ensure 5 mm separation between the adjacent turns of the heating unit.

Large electric motors may require a number of heaters on each end of the stator pack, but very large motors have the advantage that the surface to which the heaters must be fitted is reasonably smooth and continuous which improves the heat transfer efficiency.

Thus a number of heaters may be conveniently fitted at each end of a large motor, and any individual heater need only cover a semi-arc or a part circumference. In this case the heating units are usually fixed by pieces of adhesive-backed glass fibre electrical insulation tape placed across the heaters at convenient intervals.

2) Fitting of Motor Heaters

Usually motor heaters are laced onto the stator pack end turns during the manufacturing process. This is normal practice for smaller motors, but care must be taken to allow for the shrinkage of the lacing material during the impregnation process. Many polymer-based materials which are used in the construction of modern motors suffer severe contraction during the varnishing process which incorporates various heating cycles, and the tension thus created in the lacing at its final state may be sufficient to damage or cut-through the heating unit.

Alternative fixing methods use an adhesive-backed glass fibre electrical insulating tape of suitable temperature rating which is applied over the heating unit so as to fix the heating unit firmly in place. This adhesive tape must be considerably wider than the heaters. Such a fixing method is relatively inexpensive and convenient and also suitable for retro-fit operations, provided the instructions given page 1 are complied with.

On larger motors a number of heaters may be required on each end in order to provide the total nominal power input, and in this case, they may be fixed by overwrapping with adhesive tape as above, or by localised fixings with strips of adhesive tape placed across the width of the heater unit.

The heater shall be connected to earth while the motor windings is high voltage tested.

The heater shall be high voltage tested to earth at 2000V r.m.s. for 1 minute

3) Retro-fitting of Heaters

It should be noted that Type RCH/E motor heaters are the only semi-fabricated product made by RTL and they are designed as components for incorporation into the motor impregnation process. Thus if they are fitted later in the production programme, or are used as retro-fit devices, it is essential that two successive coats of varnish are applied by brush and allowed to cure before the units are commissioned in order to provide the necessary degree of thermal conductivity and moisture proofing to the heater.

Data Sheet
Current: Yes
Obsolete: No
Controlled Document

Anti-Condensation | Electric | Silicone | Sacrificial | Drum | Prices

Home Page | Top of page

Resistance Technology Limited, 8 Worrall Street, Salford,

Tel +44 (0)161 877 7345: Fax +44 (0)161 877 8711